Ink-jet recording ink, ink-jet recording ink set, ink-jet recording ink media set, ink cartridge, ink-jet recording method and ink-jet recording apparatus

ABSTRACT

An ink-jet recording ink including water, a water-soluble organic solvent, a pigment (P1) as a colorant (B), and at least one fluorochemical surfactant selected from compounds represented by Structural Formula (1) below, 
     
       
         
         
             
             
         
       
         
         
           
             where R 1  denotes any one of a hydrogen atom, an alkyl group and a fluorine-containing group, Rf denotes a fluorine-containing group, and each of x, y and z denotes an integer of 1 or greater.

TECHNICAL FIELD

The present invention relates to an ink-jet recording ink, an ink-jetrecording ink set, an ink-jet recording ink media set, an ink cartridge,an ink-jet recording method and an ink-jet recording apparatus which aresuperior in increasing image density, improving color development andreducing color bleeding on plain paper, and which are capable ofrecording high-quality images that are comparable with those produced bycommercial printing such as offset printing, when the ink-jet recordingink of the present invention is combined with a specific recordingmedium.

BACKGROUND ART

Ink-jet recording is known as a superior recording method that is notmuch affected by the types of recorded materials. Recording apparatuses,recording methods, recording materials and the like based upon ink-jetrecording have been actively studied and developed. Hitherto, inkscontaining aqueous dyes composed mainly of water have been most commonlyused for ink-jet recording inks. The inks are still most commonly usedin present-day ink-jet recording because they have many such advantagesas follows: coloring materials high in absorption coefficient and alsohigh in color purity can be easily obtained to prepare them, the inkscan be easily made multicolored so as to widen color exhibiting ranges,the inks' long-term storage stability and the inks' stability againstheat can be secured, and most notably inks capable of reducing theoccurrence of kogation can be produced.

However, since the dye inks are disadvantageous in terms ofweatherability and water resistance, studies on pigment inks thatcontain pigments instead of aqueous dyes have been remarkable in recentyears, and pigment inks are put on the market these days. Unfortunatelythough, pigment inks still remain more problematic than dye inks incolor-developing ability and stability; and along with the improvementsin techniques for increasing image quality, particularly in relation toprinters for office automation, pigment inks have been required toexhibit printing quality, hues, color saturation, glossiness, storagestability and the like on plain paper that are comparable with thoseexhibited by dye inks.

Additionally, in general, magenta inks and cyan inks used particularlyas pigment inks contain C. I. Pigment Red 122 and C. I. Pigment Blue15:3 respectively, and thus pigment inks have color reproducing rangesthat are different from those of dye inks. Also, in order to reduce hueerrors, toning is often carried out, in which case the color saturationinevitably decreases, thereby causing a problem with printing quality.

Meanwhile, in order to change hues without depending upon toning,pigments themselves are improved as well. For instance, PatentLiterature 1 proposes a cyan pigment having a hue in the same colorgamut as that of a cyan dye, by employing a phthalocyanine pigment witha specific crystal structure; however, not all requirements aresatisfied, as there are problems concerning costs, etc.

There are many other proposals including the proposal of PatentLiterature 2, which discloses an ink set wherein a pigment is used for acoloring material for a black ink, whereas dyes are used for coloringmaterials for yellow, magenta and cyan inks. However, pigment-containinginks which have satisfactory printing properties on plain paper have notyet been obtained in reality.

Additionally, as an ink set including a black ink and color inks, PatentLiterature 3 discloses an ink set including a black ink that contains aself-dispersible carbon black as a coloring material, and color inksthat contain coloring materials, wherein the coloring material for theblack ink and the coloring materials for the color inks have oppositepolarities. Further, Patent Literature 4 discloses an ink set includinginks in which colorant-containing resins are dispersed, wherein the inkshave different ionicities. However, as to printed matter produced usingthese ink sets, although bleeding on boundaries between colors can bereduced, other printing properties on plain paper still remainunsatisfactory.

Meanwhile, as a low surface-tension aqueous pigment ink with stableejection properties and improved wettability, for instance, PatentLiterature 5 proposes an ink-jet printing ink containing a water-solubleorganic solvent, a colorant, water and a perfluoroalkyl sulfonate.Additionally, as described in Patent Literature 6 to Patent Literature8, there are some proposals of ink compositions for which fluorochemicalsurfactants are used. However, all these proposals present such aproblem that in the case where pigments are used for colorants, thecolorants are inferior in dispersion stability, fixation on recordingmedia and color-developing ability. Also, in general, lowsurface-tension aqueous inks with improved wettability (including theinks of Patent Literature 5 to Patent Literature 8) present such adrawback that fluorochemical surfactants used in the inks cause the inksto foam greatly, and thus there are very serious effects on the inkfeeding capability and the ejection stability of nozzles.

As for media, conventional ink-jet paper, particularly ink-jet glossymedia, can be classified into swellable media and void-type media; thesedays, void-type media, which are superior in ink drying rate, are morepopular. As these void-type media, media each incorporating anink-absorbing layer that has voids through which ink is to be suppliedonto a substrate, and also incorporating, if necessary, a porous glossylayer are most commonly used. As disclosed in Patent Literature 9 andPatent Literature 10, each of such void-type media can be obtained asfollows: a coating solution in which silica or an alumina hydrate isdispersed is applied onto a substrate in one or more layers; and, ifnecessary, a glossy layer containing a large amount of colloidal silicais applied over the layer(s). Paper of this type is designed, withimportance being placed on its compatibility with dye inks that are mostcommonly used at present, and the paper is already widely used asink-jet paper, particularly as glossy paper. Use of the paper makes itpossible to obtain very high definition output with high glossiness; onthe other hand, since materials for the paper are very expensive andprocesses of producing the paper are complicated, the production costsof the paper are far higher than those of ordinary glossy coated paperfor commercial printing. Thus, the use of the paper tends to be limitedto cases where high-definition output such as photographic output isneeded; and in reality the paper is difficult to use in the field ofcommercial printing where a great deal of output is required at lowcosts, for example in the production of handbills, catalogues,pamphlets, etc. These days, for the sake of higher image quality, thenumber of colors of inks used in printing tends to be increased, and therequired ink absorbability tends to be increased as well. To increasethe ink absorbability of media, it is reasonable to increase thethickness of ink receiving layers (coat layers); however, the thickerthey are, the more expensive the materials therefor are, which leads toa rise in the unit prices of the media.

For pigments that form the ink-absorbing layers (receiving layers), itis necessary to use materials which are small in refractive index andhave low concealing properties, in other words which are capable ofkeeping the transparency of the layers high and which absorb largeamounts of oil (have large specific surface areas). Thus, in reality,there is no choice but to use large amounts of expensive lowrefractive-index, high oil-absorbing pigments such as silica or aluminahydrates, as opposed to inexpensive white pigments such as calciumcarbonate and kaolin. Specifically, this is because if pigments havinglow transparency and high concealing properties are used for theink-absorbing layers, coloring materials in inks that have soaked intothe ink-absorbing layers are concealed by these pigments having highconcealing properties, thereby causing a reduction in density. In fact,when paper which contains a pigment having high concealing properties issubjected to ink-jet printing with a dye ink, density is derived onlyfrom a coloring material present in the vicinity of a surface layer ofthe paper, no matter how increased the amount of ink to be applied is;thus, the density is low as a whole, and an image with little contrastis produced. Meanwhile, when a material which absorbs only a smallamount of oil is used, ink absorption is insufficient, and thus beadingeasily arises.

Accordingly, these days, attempts to achieve a favorable balance betweenthe refractive index and the whiteness are made by using fine organicparticles having a small refractive index, as disclosed in PatentLiterature 11; however, the fine organic particles, too, are high inproduction cost, and so it is still difficult to obtain inexpensive inkreceiving paper which is compatible with dye inks.

As for the design concept for long-term storage stability of imagesproduced, since dye molecules themselves are not highly resistant toultraviolet rays or ozone, such a method is most commonly employed thata dye is made to soak into an ink receiving layer of a medium as deeplyas possible so as to minimize the effects of the air and ultravioletrays, and the dye is protected with an antioxidant or stabilizerpreviously added into an image receiving layer of the medium.Accordingly, by using a large amount of ink in which the concentrationof a coloring material is relatively low, deep penetration of the ink issecured (ensured) and image storage stability is maintained.Consequently, the amount of ink necessary to output images therebyincreases, which not only makes it difficult to miniaturize cartridgesbut also raises printing costs.

Judging from the above-mentioned points, in ink-jet recording, it isvery difficult to provide inexpensive ink-jet paper and a printingmethod which are capable of high-definition output.

Meanwhile, in recent years, note has been taken of pigment inks forink-jet recording. Since pigments are insoluble in water, pigment inksin which pigments are formed as fine particles and dispersed in solventsare generally used. As pigment inks for ink-jet recording, however,pigment inks in which pigments are dispersed in water are most commonlyused in view of safety, etc. Generally, aqueous pigment inks easilycause flocculation or precipitation of pigment particles in comparisonwith dye inks; in order for the long-term storage stability of theaqueous pigment inks to be comparable with that of dye inks, variousdispersion conditions and additives are necessary; also, dispersionstabilizers cause kogation; thus, the aqueous pigment inks are difficultto use with thermal heads, and also there is such a drawback that manyof them contain coloring materials which are narrower in colorexhibiting range than dyes. Nevertheless, the aqueous pigment inks havebeen attracting more and more attention for their printing quality, suchas their capability of obtaining high black density, and for theirstorage stability and water resistance after recording. Ink-jet printersusing the pigment inks are deemed able to approximate the texture ofprinted matter to that of printed matter produced by commercial printingbecause the coloring materials contained in the pigment inks are similarto those contained in ordinary commercial printing inks; however, whencoated paper for commercial printing is actually printed with images orthe like using conventional pigment inks, the pigment inks do not dry asquickly as they should, and thus the images or the like bleed, orpigments are not fixed at all after dried, for example; consequently, asin related art, the ink-jet printers are only suitable for printing ontomedia which have high ink-absorbing properties, such as plain paper andink-jet paper. This is because the design concept concerning theformation of ink-jet images is no different from the concept in the casewhere dye inks are used; specifically, the pigments as coloringmaterials are merely viewed as dyes having high light resistance, andcharacteristics of the pigment inks are not considered at all.

Patent Literature 12 and Patent Literature 13 each disclose an imagerecording method employing an ink-jet recording method in which pigmentinks are applied onto inexpensive general-purpose paper for commercialprinting, not ink-jet paper. However the image recording method presentsthe following problems: the inks are attached in large amounts to theinexpensive general-purpose paper for commercial printing, whichnecessitates spending a great deal of time in drying the inks; moreover,in this state where the inks are excessively attached to the printingpaper surface, the inks having different colors become adjacent to oneanother before being absorbed into the printing paper, and thus bleedingbetween the different colors easily arises.

Patent Literature 14 discloses a method in which in order to produce acolor proof using an ink-jet printer, a precoating solution having afunction of flocculating a pigment is attached onto a recording mediumbefore printing is performed by the ink-jet printer. However, thismethod is problematic in that the process of attaching the precoatingsolution makes operation complicated, and also in that when theprecoating solution is attached onto the recording medium, the amount ofwater attached per unit area of the recording medium is large, whicheasily causes troubles in conveying the recording medium, such ascurling and cockling.

[Patent Literature 1] Japanese Patent Application Laid-Open (JP-A) No.2000-17207

[Patent Literature 2] JP-A No. 2000-239590

[Patent Literature 3] JP-A No. 10-140064

[Patent Literature 4] JP-A No. 2000-191972

[Patent Literature 5] JP-A No. 57-90070

[Patent Literature 6] JP-A No. 04-211478

[Patent Literature 7] JP-A No. 05-263029

[Patent Literature 8] JP-A No. 06-200200

[Patent Literature 9] JP-A No. 2005-212327

[Patent Literature 10] JP-A No. 11-078225

[Patent Literature 11] JP-A No. 2003-025717

[Patent Literature 12] JP-A No. 2002-67473

[Patent Literature 13] JP-A No. 2002-69346

[Patent Literature 14] JP-A No. 2003-211819

DISCLOSURE OF INVENTION

In light of the above-mentioned practical situations, the presentinvention is designed to achieve the following aim.

Specifically, an object of the present invention is to provide anink-jet recording ink, an ink-jet recording ink set, an ink-jetrecording ink media set, an ink cartridge, an ink-jet recording methodand an ink-jet recording apparatus, wherein a combination of afluorochemical surfactant having a specific structure and a pigment (P1)serving as a colorant (B) on plain paper makes it possible to increaseimage density, improve color development and reduce color bleeding onthe plain paper; a combination of the ink-jet pigment ink and an ink-jetrecording medium shown in the present invention makes it possible toobtain printed matter which is inexpensive, excellent in quality,superior in density, glossiness and image reliability and comparablewith commercial printed matter; and it is possible to secure superiorreliability in terms of ejection stability, storage stability and thelike.

The above-mentioned aim can be achieved by the present inventionexplained below.

<1> An ink-jet recording ink including water, a water-soluble to organicsolvent, a pigment (P1) as a colorant (B), and at least onefluorochemical surfactant selected from compounds represented byStructural Formula (1) below,

where R₁ denotes any one of a hydrogen atom, an alkyl group and afluorine-containing group, Rf denotes a fluorine-containing group, andeach of x, y and z denotes an integer of 1 or greater.

<2> The ink-jet recording ink according to <1>, further including awater-dispersible resin (A), wherein the water-soluble organic solventis at least one selected from the group consisting of glycerin,trimethylolpropane, ethylene glycol, diethylene glycol, triethyleneglycol, propylene glycol, dipropylene glycol, tripropylene glycol,1,3-butanediol, 2,3-butanediol, 1,4-butanediol, 3-methyl-1,3-butanediol,1,5-pentanediol, 1,6-hexanediol, 2-methyl-2,4-hexanediol, 2-pyrrolidone,N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, tetramethylureaand urea.<3> The ink-jet recording ink according to <2>, wherein thewater-dispersible resin (A) contains at least one of an anionicself-emulsifiable ether-based polyurethane resin emulsion and anacrylic-silicone resin emulsion.<4> An ink-jet recording ink including water, a water-soluble organicsolvent, a water-dispersible resin (A), a pigment as a colorant (B), andat least one fluorochemical surfactant selected from compoundsrepresented by Structural Formula (1) below, wherein the ink-jetrecording ink has a surface tension of 20 mN/m to 35 mN/m at 25° C. anda viscosity of 5 mPa·s or greater at 25° C., wherein the total amount ofthe water-dispersible resin (A) and the colorant (B) present in theink-jet recording ink is 5% by mass to 40% by mass, and a mass ratio(A)/(B) of the water-dispersible resin (A) to the colorant (B) is in therange of 0.5 to 4, and wherein the ink-jet recording ink is used forink-jet recording on an ink-jet recording medium for pigment ink, whichincludes a support containing cellulose pulp, and one or more pigmentpenetration preventing layers on one or both surfaces of the support,with the one or more pigment penetration preventing layers containing30% by mass or more of an inorganic pigment (P2) that is different froman alumina hydrate and that has a refractive index of 1.5 or greater,and containing 10% by mass or less of an inorganic pigment (P2) that hasa refractive index of less than 1.5,

where R₁ denotes any one of a hydrogen atom, an alkyl group and afluorine-containing group, Rf denotes a fluorine-containing group, andeach of x, y and z denotes an integer of 1 or greater.

<5> An ink-jet recording ink media set including the ink-jet recordingink according to any one of <2> to <4>, and an ink-jet recording mediumfor pigment ink, which includes a support containing cellulose pulp, andone or more pigment penetration preventing layers on one or bothsurfaces of the support, with the one or more pigment penetrationpreventing layers containing 30% by mass or more of an inorganic pigment(P2) that is different from an alumina hydrate and that has a refractiveindex of 1.5 or greater, and containing 10% by mass or less of aninorganic pigment (P2) that has a refractive index of less than 1.5.<6> An ink-jet recording ink set including a black ink, and color inks,wherein each of the black ink and the color inks is the ink-jetrecording ink according to any one of <1> to <4>.<7> The ink-jet recording ink according to <4>, wherein the one or morepigment penetration preventing layers have a thickness of 10 μm or less.<8> An ink cartridge including a container to house the ink-jetrecording ink according to any one of <1> to <6>.<9> An ink-jet recording method including performing recording with theuse of a combination of an ink-jet recording ink and a recording medium,wherein the ink-jet recording ink is the ink-jet recording ink accordingto any one of <1> to <4>, wherein the recording medium is an ink-jetrecording medium for pigment ink, which includes a support containingcellulose pulp, and one or more pigment penetration preventing layers onone or both surfaces of the support, with the one or more pigmentpenetration preventing layers containing 30% by mass or more of aninorganic pigment (P2) that is different from an alumina hydrate andthat has a refractive index of 1.5 or greater, and containing 10% bymass or less of an inorganic pigment (P2) that has a refractive index ofless than 1.5, and wherein the amount of the ink-jet recording inkattached onto the recording medium is 15 g/m² or less.<10> The ink-jet recording method according to <9>, further includingjetting the ink-jet recording ink so as to form an image on therecording medium, by applying a stimulus to the ink-jet recording ink.<11> The ink-jet recording method according to <10>, wherein thestimulus is at least one selected from heat, pressure, vibration andlight.<12> An ink-jet recording apparatus including an ink jetting unitconfigured to jet the ink-jet recording ink according to any one of <2>to <4> toward an ink-jet recording medium for pigment ink and performprinting such that the amount of the ink-jet recording ink attached ontothe recording medium is 15 g/m² or less, wherein an ink cartridge andthe ink-jet recording medium are installed in the ink-jet recordingapparatus, wherein the ink cartridge includes a container to house theink-jet recording ink, and wherein the ink-jet recording medium includesa support containing cellulose pulp, and one or more pigment penetrationpreventing layers on one or both surfaces of the support, with the oneor more pigment penetration preventing layers containing 30% by mass ormore of an inorganic pigment (P2) that is different from an aluminahydrate and that has a refractive index of 1.5 or greater, andcontaining 10% by mass or less of an inorganic pigment (P2) that has arefractive index of less than 1.5.<13> An ink-jet recording apparatus including a recording head, and aunit configured to reverse paper and thereby enable double-sidedprinting, wherein the ink-jet recording ink according to any one of <1>to <4> is ejected as droplets from the recording head so as to record animage on the paper.

According to the present invention, problems in related art can besolved, and the following can be provided: an ink-jet recording ink, anink-jet recording ink set, an ink-jet recording ink media set, an inkcartridge, an ink-jet recording method and an ink-jet recordingapparatus, wherein a combination of a fluorochemical surfactant having aspecific structure and a pigment (P1) serving as a colorant (B) on plainpaper makes it possible to increase image density, improve colordevelopment and reduce color bleeding on the plain paper; a combinationof the ink-jet pigment ink and an ink-jet recording medium shown in thepresent invention makes it possible to obtain printed matter which isinexpensive, excellent in quality, superior in density, glossiness andimage reliability and comparable with commercial printed matter; and itis possible to reduce beading and secure superior reliability in termsof ejection stability, storage stability and the like.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic diagram showing one example of an ink cartridge ofthe present invention.

FIG. 2 is a schematic diagram exemplarily showing the ink cartridge ofFIG. 1 with the inclusion of a case (outer covering).

FIG. 3 is an explanatory perspective view exemplarily showing an ink-jetrecording apparatus of the present invention when a cover provided at anink cartridge loading section is open.

FIG. 4 is a schematic structural diagram for explaining the overallstructure of an ink-jet recording apparatus of the present invention.

FIG. 5 is a schematic enlarged view showing one example of an ink-jethead of the present invention.

FIG. 6 is an enlarged view showing elements of one example of an ink-jethead of the present invention.

FIG. 7 is an enlarged cross-sectional view showing main parts of oneexample of an ink-jet head of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

The following explains in detail an ink-jet recording ink, an ink-jetrecording ink set, an ink-jet recording ink media set, an ink cartridge,an ink-jet recording method and an ink-jet recording apparatus of thepresent invention.

As a result of carrying out a series of earnest examinations to achievethe aim of increasing image density, improving color development andreducing color bleeding on plain paper, the present inventors have foundthat since an ink-jet recording ink of the present invention includes apigment (P1) as a colorant (B) and is combined with a fluorochemicalsurfactant having a specific structure, the ink-jet recording ink hashead ejection stability and is excellent in increasing image density,improving color development and reducing color bleeding on plain paper.As to the foregoing, it is inferred that when included in the ink, thefluorochemical surfactant for use in the present invention gives the inkgreat wettability, makes ink components other than the colorant quicklypenetrate into the plain paper after ink droplets have come into contactwith the plain paper, and makes the colorant remain on the papersurface, thereby yielding an increase in image density; also, it isinferred that since the ink's great wettability produces a strong effectof making the colorant remain uniformly on the plain paper, theuniformity of a solid image portion or the like improves, therebyyielding an improvement in color development. Additionally, it isinferred that the uniform penetration of the ink components other thanthe colorant into the plain paper promotes uniform fixation of thecolorant and reduces bleeding between colors. Further, it has been foundthat this fluorochemical surfactant is, due to its structure, superiorin leveling ability at the gas-liquid interface, very effective inpreventing foaming of the ink, and superior in supplying the ink to ahead, and has a great effect on ejection stability in high-speedprinting, etc.

As to fluorochemical surfactants in general, there has been concern overtheir safety and effects on the environment (e.g. accumulation of PFOSor PFOA in the human body) in recent years, and the effects are viewedas an environmental problem. However, the fluorochemical surfactant usedin the present invention is accepted by United States EnvironmentalProtection Agency (EPA) as safe for the environment, and so thefluorochemical surfactant can be suitably used in terms of safety aswell. The amount of at least one fluorochemical surfactant selected fromcompounds represented by Structural Formula (1) above, in the ink-jetrecording ink is preferably 0.01% by mass to 10% by mass, morepreferably 0.1% by mass to 5% by mass. When the amount is less than0.01% by mass, there is no remarkable effect on improvement in colordevelopment in terms of image quality. When the amount is greater than10% by mass, there is an adverse effect on dispersion of the pigmentserving as a colorant in the ink, which lowers dispersion stability andcauses thickening of the ink and flocculation of particles, and thusthere is an adverse effect on the storage stability of the ink.

(Recording Media)

Next, recording media will be explained.

Generally, ink-jet coated paper (an ink-jet medium) for realizing ahigh-quality image is designed such that an ink receiving layer (coatlayer) formed of an inorganic pigment is present on or near a basesurface, and an image is formed as the ink receiving layer itselfabsorbs ink (or ink penetrates into the ink receiving layer). This isdeeply related to the fact that ink-jet recording technologies have beendeveloped based upon dye inks.

In essence, dyes are color-developing substances that are supposed topenetrate into substances with affinity and to bond with them (covalentbond, ionic bond or van der Waals bond), whereas pigments have no (orlittle) bonding force and need to be bonded by adhesives (binders).Therefore, in the case of ink-jet recording using dye ink, ink receivinglayer material is, in effect, dyed, and this fact has promptedtechnological concepts, for example an idea of dyeing an ink receivinglayer as uniformly as possible or dyeing ink receiving layer material asmuch as possible using ink-jet ink; in order to obtain high-density,high-quality images, techniques for soaking ink-jet ink deeper into inkreceiving layers, techniques for combining ink-jet ink and ink receivinglayer material as firmly as possible, and techniques for achieving afavorable balance between ink absorbability and color-developing abilityhave been developed.

As described above, the most common method for producing present-dayink-jet paper includes forming an ink-absorbing layer which is porousand highly transparent; to realize this method, it is necessary toprimarily use a material having a low refractive index and a largespecific surface area, and in reality the ink-jet paper inevitablydepends upon an expensive material such as silica or an alumina hydrateand an elaborate production method. It goes without saying that printingcosts are very high, and application of the ink-jet paper to massprinting, etc. is difficult.

As a result of carrying out earnest studies on a lower-cost ink-jetrecording method in light of the foregoing, the present inventors havedevised a low-cost image forming method based upon a novel designconcept, realized by combining a highly penetrative pigment ink and amedium having low ink-absorbing properties, as opposed to a conventionalmedium.

Specifically, we have found that a favorable balance between sufficientimage density and drying capability can be achieved with a small amountof ink in the following manner: by conducting printing onto a recordingmedium whose ink-absorbing properties (ink penetration properties) havebeen reduced so as to prevent a pigment (P1) as a coloring material inthe ink from soaking into the recording medium as much as possible,using a small amount of extremely penetrative pigment ink, only asolvent (water and an organic solvent) that is a component of the ink isselectively soaked into a support, and only the coloring material(pigment (P1)) in the ink is made to remain efficiently on the mediumsurface.

The recording medium having reduced ink-absorbing properties in thepresent invention can be realized by providing (for example applying) alayer for preventing pigment penetration (barrier layer) on a supportcomposed mainly of cellulose pulp, in other words on a paper substrate.By approximating the appearance of this barrier layer to that ofprinting paper, it is even possible to obtain printed matter which issimilar in quality to ordinary commercial printed matter. It has beenfound that by limiting the pore size, diameter, thickness, etc. of thebarrier layer, the ink penetration properties (barrier properties) canbe reduced to a desired level.

In order to promote separation of the pigment (P1) and the ink solventin the ink, the thickness of the barrier layer is preferably less thanor equal to a predetermined thickness; specifically, the thickness ofthe barrier layer is preferably 10 μm or less, more preferably 5 μm orless. When the thickness is greater than 10 μm, penetration of the inksolvent takes a long time, beading, bleeding and the like easily arise,causing the image quality to lower, and degradation of drying capabilityeasily causes offset and the like. Also, since it is necessary to makethe barrier layer thin and therefore to prevent offset (a phenomenon inwhich the color of a coloring material printed on one side of paper canalso be seen from the other side) of the coloring material, for example,an inorganic pigment (P2) having a high refractive index and highconcealing properties needs to be contained in large amounts in thebarrier layer, as opposed to a conventional ink-jet medium;specifically, it is necessary for the barrier layer to contain 30% bymass or more of the inorganic pigment (P2) having a refractive index of1.5 or greater. Silica, a material that has a low refractive index andlow concealing properties and that is used for conventional ink-jetmedia, may be contained in the barrier layer; however, if a highlytransparent pigment (P2) is contained in large amounts in the barrierlayer, offset intensifies and the cost increases; therefore, it isnecessary for the amount of silica to be 10% by mass or less. Thus, byusing a material having a high refractive index as a white pigment thatforms the barrier layer, offset can be reduced even when the barrierlayer is made thin, and the cost can be further lowered.

Additionally, some alumina hydrates can be used as pigments having highrefractive indices; however, if a material which absorbs too much oilsuch as an alumina hydrate is contained in large amounts in the barrierlayer, the ink solvent does not easily move from the barrier layer tothe substrate. An alumina hydrate having absorbed a large amount ofsolvent is not desirable in the present invention because when storedfor a long period of time, it induces discoloration and image bleedingrelated to migration of a pigment.

The function necessary for the barrier layer in the present invention isto separate the pigment (P1) and the solvent in the ink from each otherand make only the solvent penetrate into the substrate. In order forthat to take place, it is desirable that the barrier layer have smallholes (pores). If the barrier layer has no pores whatsoever, penetrationof solvent components of the ink takes place slowly, thereby easilycausing a phenomenon in which the ink does not dry. Conversely, if poresare too large in diameter, or the number of pores is too large, thefunction of separating the pigment (P1) and the solvent in the ink fromeach other degrades, the image density decreases, and the pigment (P1)which is present on the medium surface after printing migrates into themedium with time, causing a change in color. Therefore, it is necessaryfor the pores to be 1 μm or less in diameter, and the pores preferablyoccupy 40% or less of the medium surface in area.

The pore diameter and the area of the pores with respect to the area ofthe medium surface can be measured through surface observation inaccordance with SEM. The pore diameter and the area ratio can becalculated by binarizing an image of a pore portion base upon aphotograph of the surface. In the present invention, the field-emissionscanning electron microscopes JSM-7400F (manufactured by JEOL Ltd.) andFE-SEM S-4200 (manufactured by Hitachi, Ltd.) are used as SEMs, andPOPIMAGING (ver. 3.51) (manufactured by Digital being kids Co., Ltd.) isused for image processing.

(Ink)

A pigment ink essential for the present invention is required to beextremely penetrative; at 25° C., the pigment ink has a surface tensionof 20 mN/m to 35 mN/m, preferably 23 mN/m to 33 mN/m, more preferably 25mN/m to 30 mN/m. Also, at 25° C., the pigment ink has a viscosity of 5mPa·s or greater, preferably 5 mPa·s to 15 mPa·s, more preferably 5mPa·s to 10 mPa·s. As for a surfactant used in the present invention,one or more fluorochemical surfactants each having a specific structureare contained in the ink. The total amount of a water-dispersible resin(A) and a colorant (B) present in the ink is preferably 5% by mass to40% by mass, and the mass ratio (A)/(B) of the water-dispersible resin(A) to the colorant (B) is preferably in the range of 0.5 to 4, morepreferably in the range of 1 to 2.5.

The following explains components of the ink essential for the presentinvention.

The recording ink of the present invention includes water, awater-soluble organic solvent, a pigment (P1) as a colorant (B), and afluorochemical surfactant having a specific chemical structure, andfurther includes other components in accordance with the necessity.

For the fluorochemical surfactant having the specific chemicalstructure, at least one selected from compounds represented byStructural Formula (1) below is used.

(In structural formula (1), R₁ denotes any one of a hydrogen atom, analkyl group and a fluorine-containing group, Rf denotes afluorine-containing group, and each of x, y and z denotes an integer of1 or greater.)

In Structural Formula (1), Rf denotes a fluorine-containing group,particularly preferably a perfluoroalkyl group.

<Suitable Ranges for Structural Formula (1)>

R₁: alkyl group such as methyl group or ethyl group, perfluoroalkylgroup

Rf: perfluoroalkyl group, with the number of carbon atoms being 2 or 4in the carbon chain

x, y: 1 to 4

z: 6 to 25

The following provides reasons why these ranges are suitable. As to R₁,an alkyl group having a short carbon chain or a fluorinated alkyl grouphaving a short carbon chain is favorable in view of storage stability.As to Rf, a perfluoroalkyl group having four or fewer carbon atoms isfavorable in view of safety against PFOS and PFOA, which arefluorine-based compounds, because accumulation of PFOS and PFOA in thehuman body can be prevented. As to x, y and z, when they exceed theupper limits of the ranges shown above, there is an adverse effect onstorage stability; when they are less than the lower limits of theranges shown above, the function of securing dispersion stability andantifoaming ability degrades.

The perfluoroalkyl group is preferably a perfluoroalkyl group having 1to 10 carbon atoms, more preferably a perfluoroalkyl group having 1 to 4carbon atoms in view of safety, and examples thereof include —CF₃,—CF₂CF₃, —CF₂CF₂CF₃ and —CF₂CF₂CF₂CF₃, with particular preference beinggiven to —CF₃ and —CF₂CF₃. As to R₁ that denotes any one of a hydrogenatom, an alkyl group and a fluorine-containing group, examples of thealkyl group include methyl group, ethyl group, propyl group and butylgroup, and examples of the fluorine-containing group include —CF₃,—CF₂CF₃, —CF₂CF₂CF₃ and —CF₂CF₂CF₂CF₃, with particular preference beinggiven to —CF₃ and —CF₂CF₃ in terms of improvement in image quality. Asto x, y and z, it is desirable that x and y be integers of 6 to 25 and zbe an integer of 1 to 4, and it is more desirable that x and y beintegers of 10 to 22 and z be an integer of 2 to 4 in terms of thedispersion stability of the pigment (P1) as a colorant and the storagestability of the ink.

Such a fluorochemical surfactant is different in structure fromfluorochemical surfactants (each of which is a fluorochemical surfactanthaving ammonium base sulfonates or hydroxy groups at both terminals of amain chain) described in PCT/US2006/029862 and US2007/0088101 A;examples of such a fluorochemical surfactant include AT-1202 produced byOMNOVA Solutions Inc., which can be effectively used in the presentinvention.

Also as to the ink of the present invention, the mass ratio of thecolorant (B) to the water-dispersible resin (A) is reduced and at leastone type of fluorochemical surfactant having a specific structure iscontained as a surfactant in the ink so as to improve the wettabilityand penetrability of the ink; uniformity of coloring material on paperis produced; and at least one selected from an anionic self-emulsifiableether-based polyurethane resin emulsion and an acrylic-silicone resinemulsion is contained in the water-dispersible resin (A); thus, printedmatter capable of being firmly fixed onto an inexpensive medium of thepresent invention and comparable with commercial printed matter can beachieved by a combination of the ink and the medium.

For the water-dispersible resin (A) able to be used in the presentinvention, at least one selected from a polyurethane resin emulsion andan acrylic-silicone resin emulsion, or a combination thereof issuitable. Also, the water-dispersible resin (A) is present as an O/Wemulsion when used as a raw material in preparation of the ink or afterthe ink has been prepared.

When at least one selected from a polyurethane resin emulsion and anacrylic-silicone resin emulsion is used, the emulsion/emulsions is/arepresent in the ink by a total of 1% by mass to 40% by mass, preferably atotal of 1% by mass to 20% by mass.

Polyurethane resin emulsions are classified into emulsions produced byemulsifying ordinary polyurethane resins that are relatively hydrophilicwith the external use of emulsifiers, and self-emulsifiable emulsions inwhich functional groups serving as emulsifiers are introduced intoresins themselves by copolymerization or the like. In terms of acombination of the water-dispersible resin (A) and the pigment (P1),etc. able to be used in the ink of the present invention, it is anionicself-emulsifiable polyurethane resin emulsions that are always superiorin dispersion stability. In the case where an anionic self-emulsifiablepolyurethane resin emulsion is used, it is desirable that thepolyurethane resin be based upon an ether rather than a polyester orpolycarbonate in terms of the fixation and dispersion stability of thepigment (P1). For some unknown reason, in many cases, polyurethaneresins that are not based upon ethers have little resistance to solventand thus easily cause flocculation of particles and a rise in inkviscosity when ink is stored at high temperatures.

The ether polyurethane resin emulsion has an average particle diameterof 300 nm or less, preferably 100 nm or less, more preferably 80 nm orless. In particular, by reducing its average particle diameter to 100 nmor less, it is possible to improve the reliability of an ink-jetprinter, for example ink ejection stability after the ink-jet printerhas been left unused for a long period of time.

The glass transition temperature of the ether polyurethane resinemulsion is preferably in the range of −50° C. to 150° C., morepreferably in the range of −10° C. to 100° C. For some unknown reason,when the glass transition temperature is higher than 150° C., the etherpolyurethane resin emulsion is hard like glass with respect to its filmforming properties, but a printed portion, formed as particles of thepigment (P1) and the ether polyurethane resin emulsion simultaneouslycome into contact with an image support, has unexpectedly littleabrasion resistance; when the glass transition temperature is 150° C. orlower, the ether polyurethane resin emulsion is soft like rubber withrespect to its film forming properties, but a printed portion issuperior in abrasion resistance. Meanwhile, when the glass transitiontemperature is lower than −50° C., the film is too soft and a printedportion is inferior in abrasion resistance. Thus, it has been found thatwhen there is no difference in the amount of the ether polyurethaneresin emulsion added, the range of −50° C. to 150° C. is suitable forits glass transition temperature in terms of the abrasion resistance ofprinted matter. Additionally, the glass transition temperature of theresin mentioned in the present invention can be measured in accordancewith either DSC (differential scanning calorimetry) or TMA(thermo-mechanical analysis).

The minimum film forming temperature of the ether polyurethane resinemulsion is preferably lower than or equal to room temperature, morepreferably lower than or equal to 25° C. When the ether polyurethaneresin emulsion is formed into a film at a temperature which is lowerthan or equal to room temperature, particularly at a temperature whichis lower than or equal to 25° C., it is favorable because binding ofpaper fiber automatically proceeds without the need to heat, dry, etc.an image support where an image has been formed.

Here, the “minimum film forming temperature (MFT)” is defined as theminimum temperature at which a continuous transparent film is formed,when aqueous emulsion particles obtained by dispersing etherpolyurethane resin emulsion particles into water are thinly cast onto ametal plate made of aluminum or the like and the temperature isincreased.

Next, acrylic-silicone resin emulsions able to be used in the presentinvention will be described.

The acrylic-silicone resin emulsion of the present invention is asilicone-modified acrylic resin emulsion which can be obtained bypolymerizing an acrylic monomer and a silane compound in the presence ofan emulsifier.

Examples of the acrylic monomer include acrylic acid ester monomers suchas methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexylacrylate, 2-hydroxyethyl acrylate, acryloyl morpholine andN,N′-dimethylaminoethyl acrylate; methacrylic acid ester monomers suchas methyl methacrylate, ethyl methacrylate, butyl methacrylate,2-ethylhexyl methacrylate, 2-hydroxyethyl methacrylate andN,N′-dimethylaminoethyl methacrylate; amide acrylates such asN-methylolacrylamide and methoxymethylacrylamide; and carboxylicacid-containing monomers such as maleic acid, fumaric acid, itaconicacid, acrylic acid and methacrylic acid.

Examples of the emulsifier of the present invention includealkylbenzenesulfonic acids and salts thereof, dialkylsulfosuccinic acidesters and salts thereof, alkylnaphthalenesulfon c acids and saltsthereof, formalin condensates of alkylnaphthalene sulfonates, higherfatty acid salts, sulfonates of higher fatty acid esters,polyoxypropylene-polyoxyethylene condensates of ethylenediamine,sorbitan fatty acid esters and salts thereof, aromatic/aliphaticphosphoric acid esters and salts thereof, dodecylbenzene sulfonates,dodecyl sulfates, lauryl sulfates, dialkylsulfosuccinic acid salts,polyoxyethylene alkylphenyl ether sulfates, polyoxyethylenealkylpropenylphenyl ether sulfates, alkylphenyl ether disulfonates,polyoxyethylene alkyl phosphates, polyoxyethylene alkyl ether acetates,polyoxyethylene lanolin alcohol ethers, polyoxyethylene lanolin fattyacid esters, lauryl alcohol ethoxylates, lauryl ether sulfates, laurylether phosphoric acid esters, sorbitan fatty acid esters, fatty aciddiethanol amides and formalin condensates of naphthalene sulfonic acid.Here, examples of the salts include sodium and ammonium.

Also, as the emulsifier of the present invention, a reactive emulsifierhaving an unsaturated double bond may be used as well. Examples of thereactive emulsifier include ADEKA REASOAP SE, NE and PP (produced byAsahi Denka Co., Ltd.), LATEMUL S-180 (produced by Kao Corporation),ELEMINOL JS-2 and RS-30 (produced by Sanyo Chemical Industries, Ltd.)and AQUALON RN-20 (produced by Dai-Ichi Kogyo Seiyaku Co., Ltd.).

Examples of the silane compound include tetramethoxysilane,methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane,diphenyldimethoxysilane, tetraethoxysilane, methyltriethoxysilane,dimethyldiethoxysilane, phenyltriethoxysilane, diphenyldiethoxysilane,hexyltrimethoxysilane, hexyltrimethoxysilane, decyltrimethoxysilane andtrifluoropropyltrimethoxysilane.

Also, monomers generally known as silane coupling agents may be used aswell, and examples thereof include vinyltrichlorsilane,vinyltrimethoxysilane, vinyltriethoxysilane, p-styryltrimethoxysilane,3-methacryloxypropylmethyldimethoxysilane,3-methacryloxypropyltrimethoxysilane,3-methacryloxypropylmethyldiethoxysilane,3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane,N-2(aminoethyl)3-aminopropylmethyldimethoxysilane,N-2(aminoethyl)3-aminopropyltrimethoxysilane,N-2(aminoethyl)3-aminopropyltriethoxysilane,3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane,3-triethoxysilyl-N-(1,3-dimethyl-butylidene)propylamine,N-phenyl-3-aminopropyltrimethoxysilane, hydrochlorides ofN-(vinylbenzyl)-2-aminoethyl-3-aminopropyltri ethoxysilane,3-ureidopropyltriethoxysilane, 3-chloropropyltrimethoxysilane,3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane,bis(triethoxysilylpropyl)tetrasulfide and3-isocyanatepropyltriethoxysilane.

In the present invention, the term “hydrolyzable silyl group” denotes asilyl group which contains a hydrolyzable group, and examples of thehydrolyzable group include alkoxy groups, mercapto groups, halogengroups, amide groups, acetoxy group, amino groups and isopropenoxygroup.

A silyl group hydrolyzes into a silanol group, and the silanol groupdehydrates and condenses to yield a siloxane bond. In thesilicone-modified acrylic resin used for the ink of the presentinvention, it is desirable that the hydrolyzable silyl group hydrolyzeas a result of polymerization reaction and finally disappear. If thehydrolyzable silyl group remains, it is not favorable because ofdegradation of the storage stability of the ink that has been prepared.

Fine particles of the silicone-modified acrylic resin preferably have anaverage diameter of 10 nm to 300 nm, more preferably 40 nm to 200 nm.When the ink is synthesized such that the average particle diameter isless than 10 nm, the viscosity of the resin emulsion increases, and thusit is difficult to yield an ink viscosity which enables a printer toeject the ink. When the average particle diameter is greater than 300nm, the particles clog a nozzle of the printer, and thus ejectionfailure arises.

The amount of silicone derived from the silicone-modified acrylic resin,contained in the ink of the present invention is preferably in the rangeof 100 ppm to 400 ppm. When the amount of silicone is less than 100 ppm,it is impossible to obtain a coating film superior in abrasionresistance or marker resistance. When the amount of silicone is greaterthan 400 ppm, there is an increase in hydrophobic property and adecrease in the stability of the silicone in the aqueous ink.

The minimum film forming temperature of the silicone-modified acrylicresin used in the ink of the present invention is preferably 20° C. orlower. When the minimum film forming temperature is higher than 20° C.,sufficient fixation of the ink on a printing medium cannot be yielded.In other words, if a printed portion is scratched or marked with amarker, for example, the pigment (P1) becomes separated from the printedportion, thus smearing the printing medium.

Next, the following provides an explanation of why the total amount ofthe water-dispersible resin (A) and the colorant (B) of the presentinvention present in the ink is 5% by mass to 40% by mass, and the massratio (A)/(B) of the water-dispersible resin (A) to the colorant (B) isin the range of 0.5 to 4.

Printed matter capable of being firmly fixed onto the inexpensive mediumin the present invention and comparable with commercial printed mattercan be achieved by a combination of the ink and the medium described inthe present invention; as for important factors concerning the ink inthe present invention, it has been found in the present invention thatthe total solid content of the water-dispersible resin (A) and thecolorant (B) in the ink and the ratio of the water-dispersible resin (A)to the colorant (B) are necessary factors in achieving the object.

Specifically, the total solid content of the water-dispersible resin (A)and the colorant (B) in the ink needs to be 5% by mass to 40% by mass.When the total solid content is less than 5% by mass, the ink is notsufficiently fixed onto the medium used in the present invention, forexample. When the total solid content is greater than 40% by mass, theink viscosity becomes so high that there is an adverse effect on thereliability of the ink in terms of ink ejection stability and the like.Additionally, the total solid content is preferably 5% by mass to 20% bymass. A pigment (P1) that contains resin in a dispersed manner or thatis coated with resin can also be used depending upon the type of acoloring material described below, in which case a resin dispersant orthe coating resin, and the water-dispersible resin (A) are addedtogether as the resin solid content (A).

As for the fact that the mass ratio (A)/(B) of the water-dispersibleresin (A) to the colorant (B) is in the range of 0.5 to 4, when the massratio is less than 0.5, the ink is not sufficiently fixed onto themedium used in the present invention, for example; when the mass ratiois greater than 4, the concentration of the coloring material is so lowwith respect to that of the resin that there are degradations of imagequality such as a decrease in image density and a reduction in imageuniformity. For this reason, in view of the medium used in the presentinvention, important factors concerning the ink used in the presentinvention are that the total amount of the water-dispersible resin (A)and the colorant (B) in the ink is 5% by mass to 40% by mass, and thatthe mass ratio (A)/(B) of the water-dispersible resin (A) to thecolorant (B) is in the range of 0.5 to 4. It is more desirable that themass ratio be in the range of 1 to 2.5 in terms of image quality.

Next, components constituting the ink of the present invention, andcompositions thereof will be described.

Specific examples of the water-soluble organic solvent include thefollowing compounds.

polyhydric alcohols such as ethylene glycol, diethylene glycol,triethylene glycol, propylene glycol, dipropylene glycol, tripropyleneglycol, tetraethylene glycol, polyethylene glycol, polypropylene glycol,1,3-butanediol, 3-methyl-1,3-butanediol, 2,3-butanediol, 1,4-butanediol,1,5-pentanediol, 1,6-hexanediol, glycerol, 1,2,6-hexanetriol,1,2,4-butanetriol, 1,2,3-butanetriol, 2-methyl-2,4-pentanediol, petrioland 3-methoxy-3-methyl-1-butanediol;

polyhydric alcohol alkyl ethers such as ethylene glycol monoethyl ether,ethylene glycol monobutyl ether, diethylene glycol monomethyl ether,diethylene glycol monoethyl ether, diethylene glycol monobutyl ether,tetraethylene glycol monomethyl ether and propylene glycol monoethylether;

polyhydric alcohol aryl ethers such as ethylene glycol monophenyl ether,ethylene glycol monobenzyl ether, dipropylene glycol monobutyl ether,tripropylene glycol monobutyl ether, diethylene glycol isobutyl ether,triethylene glycol isobutyl ether and diethylene glycol isopropyl ether;

nitrogen-containing heterocyclic compounds such as 2-pyrrolidone,N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone,1,3-dimethylimidazolidinone, ε-caprolactam and γ-butyrolactone;

amides such as N-methylformamide and N,N-dimethylformamide;

amines such as monoethanolamine, diethanolamine, triethanolamine,monoethylamine, diethylamine and triethylamine;

sulfur-containing compounds such as dimethyl sulfoxide, sulfolane,thiodiethanol and thiodiglycol; and

propylene carbonate and ethylene carbonate.

Among these organic solvents, particular preference is given toglycerin, ethylene glycol, diethylene glycol, triethylene glycol,propylene glycol, dipropylene glycol, tripropylene glycol,1,3-butanediol, 2,3-butanediol, 1,4-butanediol, 1,5-pentanediol,tetraethylene glycol, 1,6-hexanediol, 2-methyl-2,4-pentanediol,polyethylene glycol, 1,2,4-butanetriol, 1,2,6-hexanetriol, thiodiglycol,2-pyrrolidone, N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone and1,3-dimethyl-2-imidazolidinone. These compounds make it possible toobtain excellent effects with respect to solubility and prevention ofejection failure caused by moisture evaporation.

The pigment ink essential for the present invention includes at leastwater, a colorant in the form of particles, a fixative for the colorant,and a water-soluble organic solvent, also includes a wetting agent and asurfactant, and further includes other components in accordance with thenecessity.

As to the object of the present invention, a fluorochemical surfactanthaving a specific structure is used as the surfactant, the mass ratio ofthe colorant (B) to the water-dispersible resin (A) is lowered, and atleast one selected from an anionic self-emulsifiable ether-basedpolyurethane resin emulsion and an acrylic-silicone resin emulsion iscontained in the water-dispersible resin; thus, printed matter capableof being firmly fixed onto the inexpensive medium of the presentinvention and comparable with commercial printed matter can be achievedby a combination of the ink and the medium.

Examples of the colorant (B) include dyes such as water-soluble dyes,oil-soluble dyes and disperse dyes, and the pigment (P1). Oil-solubledyes and disperse dyes are preferable in terms of adsorption andencapsulation, while the pigment (P1) is preferable in terms of thelight resistance of images obtained.

It is desirable that each of the dyes dissolve in an organic solvent,e.g. a ketone-based solvent, at a rate of 2 g/l or greater, moredesirably at a rate of 20 g/l to 600 g/l, in view of the fact that thedyes can be efficiently encapsulated in fine polymer particles.

The colorant (B) used in the present invention will be explained below.

Examples of the pigment (P1) used in the present invention include thefollowing: as a black pigment, carbon black; as color pigments,anthraquinone, phthalocyanine blue, phthalocyanine green, diazo,monoazo, pyranthron, perylene, heterocyclic yellow, quinacridone and(thio)indigoid. Typical examples of phthalocyanine blue include copperphthalocyanine blue and derivatives thereof (Pigment Blue 15). Typicalexamples of quinacridone include Pigment Orange 48, Pigment Orange 49,Pigment Red 122, Pigment Red 192, Pigment Red 202, Pigment Red 206,Pigment Red 207, Pigment Red 209, Pigment Violet 19 and Pigment Violet42. Typical examples of anthraquinone include Pigment Red 43, PigmentRed 194 (perinone red), Pigment Red 216 (brominated pyranthron red) andPigment Red 226 (pyranthron red). Typical examples of pyrelyne includePigment Red 123 (vermillion), Pigment Red 149 (scarlet), Pigment Red 179(maroon), Pigment Red 190 (red), Pigment Violet, Pigment Red 189 (yellowshade red) and Pigment Red 224. Typical examples of thioindigoid includePigment Red 86, Pigment Red 87, Pigment Red 88, Pigment Red 181, PigmentRed 198, Pigment Violet 36 and Pigment Violet 38. Typical examples ofheterocyclic yellow include Pigment Yellow 117 and Pigment Yellow 138.Other suitable examples of coloring pigments are described in “TheColour Index, third ed., The Society of Dyers and Colourists, 1982”, forinstance.

For the pigment (P1) in the ink of the present invention, it is possibleto use a pigment that is provided with at least one hydrophilic group,which is bonded to the pigment surface directly or via other atomicgroup, and that can therefore be stably dispersed without using adispersant. The pigment (P1) of the present invention provided with ahydrophilic group, which is introduced onto the pigment surface,preferably has ionic properties, and an anionically charged pigment or acationically charged pigment is suitable for the pigment (P1).

Examples of anionic hydrophilic groups include —COOM, —SO₃M, —PO₃HM,—PO₃M₂, —SO₂NH₂ and —SO₂NHCOR (in these formulae, M denotes a hydrogenatom, an alkali metal, ammonium or an organic ammonium, and R denotes analkyl group having 1 to 12 carbon atoms, a phenyl group that may have asubstituent, or a naphthyl group that may have a substituent). In thepresent invention, among these, use of —COOM and —SO₃M, each of which isbonded to the pigment surface, is particularly preferable. Examples ofmethods for obtaining an anionically charged pigment include a method ofoxidizing a pigment with sodium hypochlorite, a method utilizingsulfonation, and a method of making a pigment and a diazonium salt reacttogether; however, it should be noted that the present invention mayemploy other methods.

As the hydrophilic group bonded to the surface of the cationicallycharged pigment (P1), a quaternary ammonium group can be used, forinstance. Ideally, a pigment provided with at least one of the followingquaternary ammonium groups, which is bonded to the pigment surface, isused as the pigment (P1).

As to the pigment (P1) used in the ink of the present invention, apigment dispersion in which the pigment (P1) is dispersed in an aqueousmedium by a dispersant can also be used. Suitable examples of thedispersant include known dispersants used in preparing pigmentdispersion solutions; specifically, the suitable examples include thefollowing compounds.

Polyacrylic acid, polymethacrylic acid, acrylic acid-acrylonitrilecopolymers, vinyl acetate-acrylic acid ester copolymers, acrylicacid-acrylic acid alkyl ester copolymers, styrene-acrylic acidcopolymers, styrene-methacrylic acid copolymers, styrene-acrylicacid-acrylic acid alkyl ester copolymers, styrene-methacrylicacid-acrylic acid alkyl ester copolymers,styrene-α-methylstyrene-acrylic acid copolymers,styrene-α-methylstyrene-acrylic acid copolymers-acrylic acid alkyl estercopolymers, styrene-maleic acid copolymers, vinylnaphthalene-maleic acidcopolymers, vinyl acetate-ethylene copolymers, vinyl acetate-fatty acidvinyl ethylene copolymers, vinyl acetate-maleic acid ester copolymers,vinyl acetate-crotonic acid copolymers and vinyl acetate-acrylic acidcopolymers.

A nonionic dispersant or an anionic dispersant used to disperse thepigment (P1) may be suitably selected according to the type of thepigment (P1) or the ink formulation; examples of the nonionic dispersantinclude polyoxyethylene alkyl ethers such as polyoxyethylene laurylether, polyoxyethylene myristyl ether, polyoxyethylene cetyl ether,polyoxyethylene stearyl ether and polyoxyethylene oleyl ether;polyoxyethylene alkylphenyl ethers such as polyoxyethylene octylphenylether and polyoxyethylene nonylphenyl ether; polyoxyethylene α-naphthylether, polyoxyethylene β-naphthyl ether, polyoxyethylenemonostyrylphenyl ether, polyoxyethylene distyrylphenyl ether,polyoxyethylene alkylnaphthyl ether, polyoxyethylene monostyrylnaphthylether, polyoxyethylene distyrylnaphthyl ether, andpolyoxyethylene-polyoxypropylene block copolymers. Also, it is possibleto use dispersants produced by replacing part of the polyoxyethylene ofthese dispersants with polyoxypropylene, and dispersants produced bycondensing aromatic ring-containing compounds such as polyoxyethylenealkylphenyl ethers, using formalin or the like.

The HLB of the nonionic dispersant is preferably in the range of 12 to19.5, more preferably in the range of 13 to 19. When the HLB is lessthan 12, the dispersant is not compatible with the dispersion medium,and thus the dispersion stability tends to degrade. When the HLB isgreater than 19.5, the dispersant does not easily adsorb to the pigment(P1), and thus the dispersion stability tends to degrade in this case aswell.

It is particularly desirable that the nonionic dispersant be selectedfrom compounds represented by Structural Formula (2) below. Bydispersing the pigment (P1) with the use of any of these compounds, theaverage particle diameter of the pigment (P1) becomes small, and theparticle size distribution can be made narrower. The polymerizationdegree n of the ethylene oxide moiety in Structural Formula (2) givenbelow is preferably in the range of 20 to 200, more preferably in therange of 25 to 60. In the case where n is less than 20, the dispersionstability lowers, the average particle diameter of the pigment (P1)becomes large, and the color saturation of images tends to decrease. Inthe case where n is greater than 200, the viscosity of the pigmentdispersion becomes high, the ink viscosity becomes high as well when anink has been prepared, and printing based upon an ink-jet recordingmethod tends to become difficult to achieve.

(In Structural Formula (2), R denotes an alkyl group having 1 to 20carbon atoms, m denotes an integer of 0 to 7, and n denotes an integerof 20 to 200.)

Examples of the alkyl group include methyl group, ethyl group, n-propylgroup, i-propyl group, n-butyl group, i-butyl group, t-butyl group,n-pentyl group, i-pentyl group, n-hexyl group, i-hexyl group, n-heptylgroup, i-heptyl group, n-octyl group, i-octyl group, n-nonyl group,i-nonyl group, n-decyl group, i-decyl group, n-undecyl group, i-undecylgroup, n-dodecyl group, i-dodecyl group, cyclopropyl group, cyclobutylgroup, cyclopentyl group, cyclohexyl group, cycloheptyl group andcyclooctyl group.

Examples of the anionic dispersant include polyoxyethylene alkyl ethersulfates, polyoxyethylene alkylphenyl ether sulfates, polyoxyethylenemonostyrylphenyl ether sulfates, polyoxyethylene distyrylphenyl ethersulfates, polyoxyethylene alkyl ether phosphates, polyoxyethylenealkylphenyl ether phosphates, polyoxyethylene monostyrylphenyl etherphosphates, polyoxyethylene distyrylphenyl ether phosphates,polyoxyethylene alkyl ether carboxylates, polyoxyethylene alkylphenylether carboxylates, polyoxyethylene monostyrylphenyl ether carboxylates,polyoxyethylene distyrylphenyl ether carboxylates, formalin condensatesof naphthalene sulfonates, formalin condensates of melanin sulfonates,dialkylsulfosuccinic acid ester salts, disodium alkyl sulfosuccinates,disodium polyoxyethylene alkylsulfosuccinates, alkylsulfoacetates,α-olefin sulfonates, alkyl benzene sulfonates, alkyl naphthalenesulfonates, alkyl sulfonates, N-acylamino acid salts, acylateddipeptides and soaps. Among these, particular preference is given tosulfates and phosphates of polyoxyethylene alkyl ethers, polyoxyethylenealkylphenyl ethers and polyoxyethylene distyrylphenyl ethers.

The amount of the dispersant added preferably equals 10% by mass to 50%by mass of the amount of the pigment (P1). When the amount of thedispersant added equals less than 10% by mass of the amount of thepigment (P1), the storage stability of the pigment (P1) dispersion andthe ink lowers, or dispersion takes a great deal of time. When theamount of the dispersant added equals more than 50% by mass of theamount of the pigment (P1), the ink viscosity becomes too high, and thusthe ejection stability tends to lower.

Further, for the colorant (B), a resin-coated colorant can also besuitably used as explained below.

The resin-coated colorant is made of a polymer emulsion in which finepolymer particles contain a coloring material which is insoluble orsparingly soluble in water. In the present specification, the expression“fine polymer particles contain a coloring material” means either orboth of a state in which the coloring material is encapsulated in thefine polymer particles, and a state in which the coloring material isadsorbed on the surface of the fine polymer particles. In this case, itis not that all of the coloring material included in the ink of thepresent invention needs to be encapsulated in or adsorbed on the finepolymer particles but that the coloring material may be dispersed in theemulsion to such an extent that the effects of the present invention arenot impaired. The coloring material is not particularly limited and maybe suitably selected in accordance with the intended use, as long as itis insoluble or sparingly soluble in water and can be adsorbed by thepolymer. In the present specification, the expression “insoluble orsparingly soluble in water” means that not more than 10 parts by mass ofthe coloring material dissolves in 100 parts by mass of water at 20° C.,whereas the term “dissolve” means that neither division norsedimentation of the coloring material is confirmed at the surface layeror bottom layer of the aqueous solution by visual observation. Examplesof the coloring material include dyes such as oil-soluble dyes anddisperse dyes, and the pigment (P1). Oil-soluble dyes and disperse dyesare preferable in terms of to adsorption and encapsulation, while thepigment (P1) is preferable in terms of the light resistance of imagesobtained.

It is desirable that the colorant (B) of the present invention dissolvein an organic solvent, e.g. a ketone-based solvent, at a rate of 2 g/lor greater, more desirably at a rate of 20 g/l to 600 g/l, in view ofthe fact that the colorant (B) can be efficiently encapsulated in finepolymer particles. Examples of the polymer constituting the polymeremulsion include vinyl-based polymers, polyester-based polymers andpolyurethane-based polymers. Among these, particular preference is givento vinyl-based polymers and polyester-based polymers, specifically thepolymers disclosed in JP-A Nos. 2000-53897 and 2001-139849. The amountof the colorant is preferably 10 parts by mass to 200 parts by mass,more preferably 25 parts by mass to 150 parts by mass, per 100 parts bymass of the polymer. The fine polymer particles containing the colorantpreferably have an average diameter of 0.16 μm or less in the ink.

The amount of the fine polymer particles contained in the recording inkis preferably 8% by mass to 20% by mass, more preferably 8% by mass to12% by mass, as a solid content.

As the colorant used in the present invention, the pigment (P1) is mostfavorable. Meanwhile, for the resin-coated colorant, a dye can be usedas well. The following shows a set of examples of water-soluble dyes. Itis desirable that those superior in water resistance and lightresistance be used.

Specific examples of the dyes include acid dyes and food dyes such asC.I. Acid Yellow 17, 23, 42, 44, 79 and 142; C.I. Acid Red 1, 8, 13, 14,18, 26, 27, 35, 37, 42, 52, 82, 87, 89, 92, 97, 106, 111, 114, 115, 134,186, 249, 254 and 289; C.I. Acid Blue 9, 29, 45, 92 and 249; C.I. AcidBlack 1, 2, 7, 24, 26 and 94; C.I. Food Yellow 3 and 4; C.I. Food Red 7,9 and 14; and C.I. Food Black 1 and 2.

Specific examples of the dyes include direct dyes such as C.I. DirectYellow 1, 12, 24, 26, 33, 44, 50, 86, 120, 132, 142 and 144; C.I. DirectRed 1, 4, 9, 13, 17, 20, 28, 31, 39, 80, 81, 83, 89, 225 and 227; C.I.Direct Orange 26, 29, 62 and 102; C.I. Direct Blue 1, 2, 6, 15, 22, 25,71, 76, 79, 86, 87, 90, 98, 163, 165, 199 and 202; and C.I. Direct Black19, 22, 32, 38, 51, 56, 71, 74, 75, 77, 154, 168 and 171.

Specific examples of the dyes include basic dyes such as C.I. BasicYellow 1, 2, 11, 13, 14, 15, 19, 21, 23, 24, 25, 28, 29, 32, 36, 40, 41,45, 49, 51, 53, 63, 64, 65, 67, 70, 73, 77, 87 and 91; Basic Red 2, 12,13, 14, 15, 18, 22, 23, 24, 27, 29, 35, 36, 38, 39, 46, 49, 51, 52, 54,59, 68, 69, 70, 73, 78, 82, 102, 104, 109 and 112; C.I. Basic Blue 1, 3,5, 7, 9, 21, 22, 26, 35, 41, 45, 47, 54, 62, 65, 66, 67, 69, 75, 77, 78,89, 92, 93, 105, 117, 120, 122, 124, 129, 137, 141, 147 and 155; andC.I. Basic Black 2 and 8.

Specific examples of the dyes include reactive dyes such as C.I.Reactive Black 3, 4, 7, 11, 12 and 17; C.I. Reactive Yellow 1, 5, 11,13, 14, 20, 21, 22, 25, 40, 47, 51, 55, 65 and 67; C.I. Reactive Red 1,14, 17, 25, 26, 32, 37, 44, 46, 55, 60, 66, 74, 79, 96 and 97; and C.I.Reactive Blue 1, 2, 7, 14, 15, 23, 32, 35, 38, 41, 63, 80 and 95.

In the present invention, use of a surfactant, notably thefluorochemical surfactant having a specific structure, makes it possibleto improve the wettability and penetrability of the ink to recordingpaper. Fluorochemical surfactants are generally known to have highfoaming properties, and inks containing those fluorochemical surfactantseasily foam in many cases, causing adverse effects on the ink feedingcapability and the ink ejection stability; however, the fluorochemicalsurfactant having a specific structure in the present invention isreduced in foaming property, superior in ink feeding capability and inkejection stability and excellent in safety, and makes it possible toyield high color-developing properties and uniformity of a coloringmaterial on the ink-jet recording medium used in the present patent andreduce beading greatly, and thus excellent images can be obtained.Although details as to why its effectiveness can be obtained are notknown, it is inferred that the fluorochemical surfactant having aspecific structure in the present invention is, due to its structure,superior in leveling ability, highly effective in making uniform thesurface tension at the gas-liquid interface, and therefore superior inantifoaming ability, and that the leveling ability has an effect ofevenly dispersing the coloring material and evenly enlarging imageelement diameters in a wet manner on the ink-jet recording medium, whichenables beading to be greatly reduced, thereby making it possible toprovide an ink-jet recording ink, an ink-jet recording ink set, anink-jet recording ink media set, an ink cartridge, an ink-jet recordingmethod and an ink-jet recording apparatus, wherein a combination of theink-jet pigment ink and the ink-jet recording medium shown in thepresent invention makes it possible to obtain printed matter which isinexpensive, excellent in quality, superior in density, glossiness andimage reliability and comparable with commercial printed matter, and itis possible to secure superior reliability in terms of ejectionstability, storage stability and the like.

In addition to the fluorochemical surfactant represented by StructuralFormula (1) in the present invention, any of the followingfluorochemical surfactants can be used: perfluoroalkyl sulfonates,perfluoroalkyl carboxylates, perfluoroalkyl phosphoric acid esters,perfluoroalkyl ethylene oxide adducts, perfluoroalkyl betaine,perfluoroalkyl amine oxide compounds and the like. Examples of thosewhich are commercially available as fluorine-based compounds, easilyobtainable and able to be used in the present invention include SURFLONS-111, S-112, S-113, 5121, 5131, S132, S-141 and S-145 (produced byAsahi Glass Co., Ltd.), FLUORAD FC-93, FC-95, FC-98, FC-129, FC-135,FC-170C, FC-430, FC-431 and FC-4430 (produced by Sumitomo 3M Limited),MEGAFAC F-470, F-1405 and F474 (produced by Dainippon Ink And Chemicals,Incorporated), ZONYL FS-300, FSN, FSN-100 and FSO (produced by E. I. duPont de Nemours and Company), and EFTOP EF-351, 352, 801 and 802(produced by JEMCO Inc.). Among these, particular preference is given toZONYL FS-300, FSN, FSN-100 and FSO (produced by E. I. du Pont de Nemoursand Company), which are excellent in reliability and improving colordevelopment.

Examples of surfactants able to be used in addition to theabove-mentioned fluorochemical surfactants include interfacialpolyoxyethylene alkyl ether acetates, dialkyl sulfosuccinates,polyoxyethylene alkyl esters, polyoxyethylene alkylphenyl ethers,polyoxyethylene-polyoxypropylene block copolymers, polyoxyethylene alkylesters, polyoxyethylene sorbitan fatty acid esters and acetyleneglycol-based surfactants. More specifically, as to anionic surfactants,use of a polyoxyethylene alkyl ether acetate and/or a dialkylsulfosuccinate having a branched alkyl chain whose carbon chain has 5 to7 carbon atoms makes it possible to improve the wettability of the inkto plain paper. Note that any of these surfactants can be stably presentin the ink of the present invention without disturbing the dispersedstate of ingredients.

A polyol having 7 to 11 carbon atoms, used as a penetrant in the presentinvention, can be any one of 2-ethyl-1,3-hexanediol and2,2,4-trimethyl-1,3-pentanediol, for example. The amount of the polyoladded is preferably in the range of 0.1% by mass to 20% by mass, morepreferably in the range of 0.5% by mass to 10% by mass. When the amountis smaller than or equal to the lower limit, the penetrability of theink to paper degrades; therefore, the paper may be smeared whenconveyed, as recorded matter is possibly scratched by a roller, or thepaper may be smeared when reversed for double-sided printing, as the inkis possibly attached to a conveyance belt, and thus it is impossible tosecure sufficient adaptability to high-speed printing or double-sidedprinting. When the amount is greater than or equal to the upper limit,there may be an increase in printing dot diameter, thereby possiblycausing the line width of letters/characters to increase, or causing theimage clarity to decrease.

Examples of additives include an antifungal agent, an antirust agent anda pH adjuster.

Use of 1,2-benzisothiazolin-3-one as an antifungal agent makes itpossible to provide an ink capable of securing reliability in terms ofstorage stability, ejection stability and the like, and superior inantifungal effect. Especially when combined with the wetting agent ofthe present invention, the antifungal agent can be sufficientlyeffective even if its amount is deemed too small in related art toreduce the generation of germs or fungi; thus, by reducing the amount ofthe antifungal agent added, it becomes possible to prevent suchphenomena as flocculation of particles and thickening of ink, and so theperformance of the ink can be maintained for a long period of time. Asan active ingredient amount, the amount of 1,2-benzisothiazolin-3-oneadded is preferably 0.01 parts by mass to 0.04 parts by mass in relationto the total amount of the ink. In the case where the amount is lessthan 0.01 parts by mass, there is a slight reduction in antifungalproperty. In the case where the amount is 0.04 parts by mass or greater,flocculation of particles arises or the ink viscosity increases by 50%to 100% in comparison with the initial ink viscosity, when the ink isstored for a long period of time (e.g. for two years at roomtemperature, or for one to three months at a temperature of 50° C. to60° C.), for example; hence, there is a problem with the long-termstorage stability of the ink, and the initial printing performancecannot be maintained.

For the pH adjuster, any substance may be used as long as it can adjustthe pH to 7 or greater without having an adverse effect on the ink to beprepared.

Examples of the pH adjuster include amines such as diethanolamine andtriethanolamine; hydroxides of alkali metals such as lithium hydroxide,sodium hydroxide and potassium hydroxide; ammonium hydroxide, hydroxidesof quaternary ammonium, and hydroxides of quaternary phosphonium;carbonates of alkali metals such as lithium carbonate, sodium carbonateand potassium carbonate; and aminopropanediol derivatives.Aminopropanediol derivatives are water-soluble organic basic compounds,and examples thereof include 1-amino-2,3-propanediol,1-methylamino-2,3-propanediol, 2-amino-2-methyl-1,3-propanediol and2-amino-2-ethyl-1,3-propanediol, with particular preference being givento 2-amino-2-ethyl-1,3-propanediol.

Examples of the antirust agent include acid sulfites, sodiumthiosulfate, ammonium thiodiglycolate, diisopropylammonium nitrite,pentaerythritol tetranitrate and dicyclohexylammonium nitrite.

Also, a water-soluble ultraviolet absorber, a water-soluble infraredabsorber or the like may be added to the antirust agent in accordancewith the intended use.

(Ink-Jet Recording)

In the present invention, the total amount of the ink needs to bestrictly controlled in order to secure drying properties of the ink aswell as to prevent the coloring material (pigment (P1)) in the ink fromsoaking into a medium and efficiently make the coloring material presentin the vicinity of the medium surface; if a large amount of ink is usedas in conventional ink-jet recording, the pigment (P1) in the inkpossibly penetrates into the medium along with the ink solvent becausethe pigment separating ability of a barrier layer becomes insufficientfor the large amount of ink, or there is possibly a great problem withthe ink drying capability because solvent components of the ink may notpenetrate into the medium as quickly as they should. It has turned outthat in view of the barrier layer performing its function, the totalamount of ink is 15 g/m² at the most, preferably 12 g/m² or less. Theink amount can be easily adjusted by controlling the amount of thepenetrant (EHD) and the amount of the fluorochemical surfactant, etc.Also, by reducing the total amount of ink necessary for printing, it ispossible to make the capacity of an ink cartridge smaller than in aconventional ink-jet printer and thus to make an apparatus compact.Additionally, when an ink cartridge having a size similar to that of aconventional ink cartridge is used, the rate at which the ink cartridgeis replaced can be reduced, and thus printing becomes possible at alower cost. Basically, the smaller the total amount of ink is, thegreater the pigment separating ability of the barrier layer is; however,if the total amount of ink is too small, there is such a drawback thatthe image dot diameter becomes too small after printing, so that it isdesirable to set the total amount of ink within the above-mentionedrange in accordance with a desired image.

In the present invention, the total amount of ink is measured inaccordance with a weight method. Specifically, a 5 cm×20 cm rectangle isprinted onto a sheet of TYPE 6200 (produced by Ricoh Company, Ltd.),which is PPC paper, then the weight of the printed sheet is measuredimmediately after the printing, the weight of the sheet before theprinting is subtracted from the measured weight, and the obtained valueis multiplied by 100 so as to serve as the total amount of ink.

The highly penetrative ink of the present invention can also be used forprinting onto a conventional void-type ink-jet medium. It should,however, be noted that since the ink absorption rate is far higher thanin the case where the ink is used for printing onto the recording mediumof the present invention, the solvent penetrates into the void-typeink-jet medium before dots spread in a wet manner, after ink dropletshave come into contact with the medium surface, and thus the dotdiameter becomes small. Consequently, the image density easilydecreases, and particles become easier to notice in an image. Thus,production of a high-quality image requires printing which is higher inresolution than printing onto the recording medium of the presentinvention, thereby leading to a decrease in printing speed and anincrease in ink consumption. Hence, it is desirable to use the recordingmedium of the present invention.

(Recording Media)

Examples of the inorganic pigment (P2) contained in the barrier layer inthe present invention include magnesium carbonate, talc, kaolin, illite,clay, calcium carbonate, calcium sulfite, titanium white, magnesiumcarbonate and titanium dioxide. Each of these pigments (P2) preferablyhas an average particle diameter of 3 μm or less. Use of a pigment witha relatively high refractive index among these pigments (P2) makes itpossible to reduce the thickness of the barrier layer. In terms of cost,use of calcium carbonate or kaolin is preferable. These pigments (P2)may be used in combination as long as the effects of the presentinvention are not impaired; also, these pigments (P2) may be combinedwith other pigments (P2) not included in the above-mentioned examples.Kaolin is preferable in that it is superior in gloss developing propertyand makes it possible to yield a texture which approximates that ofpaper for offset printing. Examples of the kaolin include delaminatedkaolin, calcined kaolin, and engineered kaolin produced by surfacemodification or the like. In view of gloss developing properties, it isdesirable that 50% by mass or more of the whole kaolin be occupied bykaolin having a particle size distribution in which 80% by mass or moreof the particles are 2 μm or less in diameter. The amount of the kaolincontained is preferably 50 parts by mass or more. When the amount isless than 50 parts by mass, sufficient effectiveness may not be obtainedwith respect to glossiness.

Although the upper limit of the amount of the kaolin contained is notparticularly limited, it is desirable in terms of coating suitabilitythat the amount be less than 90 parts by mass, in view of the kaolin'sfluidity, especially thickening properties in the presence of highshearing force.

These pigments (P2) that have high refractive indices may be used incombination with silica and/or organic pigments (P2) that have lowrefractive indices. Examples of the organic pigments (P2) includewater-soluble dispersions containing styrene-acrylic copolymerparticles, styrene-butadiene copolymer particles, polystyrene particles,polyethylene particles, etc. Each of these organic pigments (P2) may beused in combination with two or more. The organic pigments (P2) aresuperior in gloss developing property and smaller in specific gravitythan the inorganic pigments (P2), thereby making it possible to obtaincoating layers which are bulky, highly glossy and excellent in surfacecoating property; the amount of any of the organic pigments (P2) addedis preferably 2 parts by mass to 5 parts by mass. When the amount isless than 2 parts by mass, such effects cannot be obtained. When theamount is greater than 5 parts by mass, ink strike-through is liable toarise, and also the cost will rise, which is economically unfavorable.Examples of the forms of the organic pigments (P2) include dense type,hollow type and doughnut type; in light of a balance among the glossdeveloping property, the surface coating property, and the fluidity ofcoating solution, it is desirable that the organic pigments (P2) be inthe range of 0.2 μm to 3.0 μm in average particle diameter, and it isfurther desirable to employ a hollow-type organic pigment having a voidratio of 40% or more.

The binder of the layer for preventing pigment penetration (barrierlayer) used in the present invention is not particularly limited as longas it firmly adheres to the pigment and base paper that constitute thebarrier layer and it is made of an aqueous resin, an emulsion or thelike which does not cause blocking.

Examples of the aqueous binder include polyvinyl alcohol; starches suchas starch oxide, esterified starch, enzyme-modified starch andcationated starch; cellulose derivatives such as casein, soya beanproteins, carboxymethyl cellulose and hydroxyethyl cellulose; andstyrene-acrylic copolymer resins, isobutylene-maleic anhydride copolymerresins, acrylic emulsions, vinyl acetate emulsions, vinylidene chlorideemulsions, polyester emulsions, styrene-butadiene copolymer latex andacrylonitrile-butadiene copolymer latex. Among these, use of starches orstyrene-butadiene copolymer latex is preferable in terms of cost. Thestyrene-butadiene copolymer latex contains styrene and butadiene asmonomers, and these monomers may be copolymerized with other monomersaccording to the necessity, or the styrene-butadiene copolymer latex maybe copolymer latex commonly used for paper coating, in which thecopolymer has been modified by chemical reaction. Typical examples ofthe other monomers include vinyl-based monomers such as acrylic acid,methacrylic acid, alkyl esters of (meth)acrylic acid, acrylonitrile,maleic acid, fumaric acid and vinyl acetate. Also, the styrene-butadienecopolymer latex may contain a cross-linking agent such as methylolatedmelamine, methylolated urea, methylolated hydroxypropylene urea orisocyanate or may be a copolymer with self-crosslinking ability thatincludes N-methylolacrylamide or other unit. Each of these may be usedalone or in combination with two or more.

The amount of the aqueous binder added into the barrier layer in thepresent invention is preferably 50% by mass to 70% by mass, morepreferably 55% by mass to 60% by mass, in relation to the total coatinglayer solid content. When the amount is smaller than the lower limit,the barrier layer is deficient in adhesion, and thus there is concernthat the strength of the ink receiving layer might decrease, theinternal bonding strength might decrease, and detachment of particlesmight arise.

Further, other components may be added to the barrier layer of thepresent invention in accordance with the necessity, to such an extentthat the object and effects of the present invention are not impaired.Examples of the other components include auxiliary agents contained inpigments for ordinary coated paper, such as a dispersant, a thickener, awater retention agent, an antifoaming agent and a water resistantadditive; and additives such as a pH adjuster, an antiseptic agent, anantioxidant and a cationic organic compound.

A surfactant used in the barrier layer is not particularly limited andmay be suitably selected in accordance with the intended use. For thesurfactant, any one of an anionic surfactant, a cationic surfactant, anamphoteric surfactant and a nonionic surfactant may be used, withparticular preference being given to a nonionic surfactant.

Examples of the nonionic surfactant include higher alcohol ethyleneoxide adducts, alkylphenol ethylene oxide adducts, fatty acid ethyleneoxide adducts, polyhydric alcohol fatty acid ester ethylene oxideadducts, higher aliphatic amine ethylene oxide adducts, fatty acid amideethylene oxide adducts, ethylene oxide adducts of fats, polypropyleneglycol ethylene oxide adducts, fatty acid esters of glycerol, fatty acidesters of pentaerythritol, fatty acid esters of sorbitol and sorbitan,fatty acid esters of sucrose, alkyl ethers of polyhydric alcohols, andfatty acid amides of alkanolamines. Each of these may be used alone orin combination with two or more.

The polyhydric alcohols are not particularly limited and may be suitablyselected in accordance with the intended use. Examples thereof includeglycerol, trimethylolpropane, pentaerythrite, sorbitol and sucrose. Asto the ethylene oxide adducts, ones in which an alkylene oxide, forexample propylene oxide or butylene oxide, is substituted for part ofethylene oxide to such an extent that their water solubility can bemaintained are also effective; in this case, the substitution ratio ispreferably 50% or less. The HLB (hydrophile-lipophile balance) of thenonionic surfactant is preferably 4 to 15, more preferably 7 to 13.

A cationic organic compound is not necessarily required, and a cationicorganic compound is not particularly limited and may be suitablyselected in accordance with the intended use.

Examples of the cationic organic compound includedimethylamine-epichlorhydrin polycondensates,dimethylamine-ammonia-epichlorhydrin condensates,poly(triethylaminoethyl methacrylate-methylsulfate), diallylaminehydrochloride-acrylamide copolymers, poly(diallylaminehydrochloride-sulfur dioxide), polyallylamine hydrochloride,poly(allylamine hydrochloride-diallylamine hydrochloride),acrylamide-diallylamine copolymers, polyvinylamine copolymers,dicyandiamide, dicyandiamide-ammonium chloride-urea-formaldehydecondensates, polyalkylene polyamine-dicyandiamide ammonium saltcondensates, dimethyldiallylammonium chloride, polydiallylmethylaminehydrochloride, poly(diallyldimethylammonium chloride),poly(diallyldimethylammonium chloride-sulfur dioxide),poly(diallyldimethylammonium chloride-diallylamine hydrochloridederivatives), acrylamide-diallyldimethylammonium chloride copolymers,acrylate-acrylamide-diallylamine hydrochloride copolymers,polyethylenimine, ethylenimine derivatives such as acrylamine polymers,and modified products of polyethylenimine alkylene oxides. Each of thesemay be used alone or in combination with two or more.

The support used in the present invention is produced by mixing togetherchemical pulp, mechanical pulp, recycled pulp and the like with anarbitrary ratio, and the raw materials to which an internally addedsizing agent, a yield improver, a paper strength increasing agent andthe like have been added in accordance with the necessity are made intopaper using, for example, a fourdrinier former, a gap-type twin-wireformer, or a hybrid former in which a posterior portion of a fourdriniersection is composed of twin wires.

The pulp used in the support of the present invention may contain avirgin chemical pulp (CP), for example one produced by chemicallytreating a wood material such as leaf bleached kraft pulp, needlebleached kraft pulp, leaf unbleached kraft pulp, needle unbleached kraftpulp, leaf bleached sulfite pulp, needle bleached sulfite pulp, leafunbleached sulfite pulp or needle unbleached sulfite pulp, or otherfiber raw material; and a virgin mechanical pulp (MP), for example oneproduced by mechanically treating a wood material such as ground pulp,chemiground pulp, chemimechanical pulp or semi-chemical pulp, or otherfiber raw material.

Also, recycled pulp may be used as well, and examples of the rawmaterial for the recycled pulp include articles shown in the “Used PaperStandard Quality Specification List” released by Paper RecyclingPromotion Center, such as high-quality white paper, white paper withlines and marks, cream-colored paper, card, medium-quality white paper,low-quality white paper, simili paper, white-colored paper, Kent paper,white art paper, medium-quality colored paper, low-quality coloredpaper, newspaper and magazine.

Specific examples thereof include used paperboards and used papers ofthe following papers: printer papers such as uncoated computer paper,thermosensitive paper and pressure-sensitive paper that are related toinformation; OA (office automation) related papers such as paper for PPC(plain paper copier); coated papers such as art paper, coated paper,finely coated paper and matte paper; and uncoated papers such ashigh-quality paper, high color quality paper, notebook, letter paper,packing paper, fancy paper, medium-quality paper, newspaper, woodypaper, super wrapping paper, simili paper, pure white roll paper andmilk carton. More specific examples thereof include chemical pulp paperand high-yield pulp-containing paper. Each of these may be used alone orin combination with two or more.

The recycled pulp is generally produced by a combination of thefollowing four steps.

(1) Defibration: used paper is treated with mechanical force andchemicals using a pulper and thusly fiberized, and printing ink isseparated from the fiber.

(2) Dust removal: foreign matter (plastic, etc.) and dust contained inthe used paper is removed by a screen, a cleaner or the like.

(3) Ink removal: the printing ink that has been separated from the fiberusing a surfactant is removed from the system by a flotation method orwashing method.

(4) Bleaching: the whiteness of the fiber is enhanced utilizingoxidation or reduction.

When the recycled pulp is mixed with other pulp, it is desirable thatthe mixture ratio of the recycled pulp in the whole pulp be 40% or lessso as to prevent curl after recording.

For a filler able to be used in the support of the present invention,use of calcium carbonate is effective, and the following materials maybe additionally used: inorganic fillers exemplified by silicates such askaolin, fired clay, pyrophyllite, sericite and talc; and organicpigments (P2) such as satin white, barium sulfate, calcium sulfate, zincsulfide, plastic pigments and urea resins.

The internally added sizing agent used in the support of the presentinvention is not particularly limited and may be suitably selected fromknown internally added sizing agents used for ink-jet recording paper.Suitable examples of the internally added sizing agent include rosinemulsion sizing agents. Examples of the internally added sizing agentused in producing the support include neutral rosin sizing agents usedin neutral papermaking, alkenyl succinic anhydrides (ASA), alkyl ketenedimers (AKD) and petroleum resin sizing agents. Among these, neutralrosin sizing agents and alkenyl succinic anhydrides are particularlysuitable. Although the alkyl ketene dimers can be added in small amountsdue to their strong sizing effects, they may be unfavorable in terms ofpaper conveyance at the time of inkjet recording because the frictioncoefficient of the recording paper (medium) surface decreases and thusthe surface easily becomes slippery.

The amount of the internally added sizing agent used is preferably 0.1parts by mass to 0.7 parts by mass per 100 parts by mass of bone-drypulp; however, the amount is not limited thereto.

For the internally added filler in the support, a pigment which isconventionally known as a white pigment (P2) is used, for instance.Examples of the white pigment (P2) include white inorganic pigments (P2)such as light calcium carbonate, heavy calcium carbonate, kaolin, clay,talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide,zinc sulfide, zinc carbonate, satin white, aluminum silicate,diatomaceous earth, calcium silicate, magnesium silicate, syntheticsilica, aluminum hydroxide, alumina, lithopone, zeolite, magnesiumcarbonate and magnesium hydroxide; and organic pigments (P2) such asstyrene-based plastic pigments, acrylic plastic pigments, polyethylene,microcapsules, urea resins and melamine resins. Each of these may beused alone or in combination with two or more.

<Method for Producing Barrier Layer>

The method for providing the barrier layer over the support of thepresent invention by coating is not particularly limited. For instance,it is possible to utilize a method of directly coating a support with abarrier layer, a method in which a barrier layer that has been appliedonto another base material is transferred onto original paper, or amethod of applying a barrier layer in the form of a mist, using a sprayor the like. Examples of the method of directly coating a support with abarrier layer include film transfer methods such as roll coater method,air knife coater method, gate roll coater method, size pressing,Symsizer method, and rod metalling size press coater method; and bladecoater methods such as fountain method and roll application.

The barrier layer can be dried using a hot-air drying oven or a thermaldrum, for instance. Further, the barrier layer may be subjected to asurface-finishing process using a calendering device (supercalender,soft calender, gloss calender, etc.) so as to flatten its surface orincrease the strength of its surface.

The barrier layer of the present invention can be provided by coating,as described above; in addition, as a result of carrying out an earneststudy, the present inventors have found that the barrier layer of thepresent invention can also be produced by polishing the surface ofexisting coated paper for printing. It is inferred that this is possiblebecause the thickness of the coat layer is reduced by the polishing tothe thickness shown in the present invention, a resin layer present onthe outermost surface is shaved, which makes pores appear, and thus alayer functioning as a barrier layer is obtained.

The existing coated paper for printing denotes coated paper used forcommercial printing exemplified by offset printing, gravure printing,etc., and examples thereof include art paper (A0, A1), A2 coated paper,A3 coated paper, B2 coated paper, light coated paper and finely coatedpaper.

The following shows examples of the coated paper as specific products.Examples thereof as art paper include OK KINFUJI N, OK KINFUJI-R40N, SAKINFUJI N, SATIN KINFUJI N, SATIN KINFUJI-R40N, ULTRA-SATIN KINFUJI N,ULTRA-OK KINFUJI N and KINFUJI SINGLE SIDE (produced by Oji paper Co.,Ltd.); NPi SPECIAL ART, NPi SUPER ART, NPi SUPER DULL and NPi DULL ART(produced by Nippon Paper Group, Inc.); UTRILLO SUPER ART, UTRILLO SUPERDULL and UTRILLO PREMIUM (produced by Daio Paper Corporation);HIGH-GRADE ART A, SPECIAL MITSUBISHI ART, SUPER MAT ART A and HIGH-GRADEDULL ART A (produced by Mitsubishi Paper Mills Limited); and RAICHOSUPER ART N, RAICHO SUPER ART MN, RAICHO SPECIAL ART and RAICHO DULL ARTN (produced by Chuetsu Pulp & Paper Co., Ltd.).

Examples thereof as A2 coated paper include OK TOP COAT+(PLUS), OK TOPCOAT S, OK CASABLANCA, OK CASABLANCA V, OK TRINITY, OK TRINITY NAVI, NEWAGE, NEW AGE W, OK TOP COAT MATT N, OK ROYAL COAT, OK TOP COAT DULL, ZCOAT, OK KASAHIME, OK KASAO, OK KASAO SATIN, OK TOP COAT+, OKNON-WRINKLE, OK COAT V, OK COAT N GREEN 100, OK MATT COAT GREEN 100, NEWAGE GREEN 100 and Z COAT GREEN 100 (produced by Oji paper Co., Ltd.);AURORA COAT, SHIRAOI MATT, IMPERIAL MATT, SILVER DIAMOND, RECYCLE COAT100 and CYCLE MATT 100 (produced by Nippon Paper Group, Inc.); μ COAT, μWHITE, μ MATT and WHITE μ MATT (produced by Hokuetsu Paper Mills, Ltd.);RAICHO COAT N, REGINA RAICHO COAT 100, RAICHO MATT COAT N and REGINARAICHO MATT 100 (produced by Chuetsu Pulp & Paper Co., Ltd.); and PEARLCOAT, WHITE PEARL COAT N, NEW V MATT, WHITE NEW V MATT, PEARL COAT REW,WHITE PEARL COAT NREW, NEW V MATT REW and WHITE NEW V MATT REW (producedby Mitsubishi Paper Mills Limited).

Examples thereof as A3 coated (light coated) paper include OK COAT L,ROYAL COAT L, OK COAT LR, OK WHITE L, OK ROYAL COAT LR, OK COAT L GREEN100 and OK MATT COAT L GREEN 100 (produced by Oji paper Co., Ltd.);EASTER DX, RECYCLE COAT L100, AURORA L, RECYCLE MATT L100 and <SSS>ENERGY WHITE (produced by Nippon Paper Group, Inc.); UTRILLO COAT L andMATISSE COAT (produced by Daio Paper Corporation); HIGH-ALPHA, ALPHAMATT, (N) KINMARI L and KINMARI HiL (produced by Hokuetsu Paper Mills,Ltd.); N PEARL COAT L, N PEARL COAT LREW and SWING MATT REW (produced byMitsubishi Paper Mills Limited); and SUPER EMINE, EMINE and SHATON(produced by Chuetsu Pulp & Paper Co., Ltd.).

Examples thereof as B2 coated (medium-quality coated) paper include OKMEDIUM-QUALITY COAT, (F) MCOP, OK ASTRO GLOSS, OK ASTRO DULL and OKASTRO MATT (produced by Oji paper Co., Ltd.); and KING O (produced byNippon Paper Group, Inc.).

Examples thereof as finely coated paper include OK ROYAL LIGHT S GREEN100, OK EVER LIGHT COAT, OK EVER LIGHT R, OK EVER GREEN, CLEAN HIT MG,OK FINE COATING SUPER ECO G, ECO GREEN DULL, OK FINE COATING MATT ECOG100, OK STAR LIGHT COAT, OK SOFT ROYAL, OK BRIGHT, CLEAN HIT G,YAMAYURI BRIGHT, YAMAYURI BRIGHT G, OK AQUA-LIGHT COAT, OK ROYAL LIGHT SGREEN 100, OK BRIGHT (Rough And Glossy), SNOW MATT, SNOW MATT DX, OKKASAHIME and OK KASAYURI (produced by Oji paper Co., Ltd.); PYRENE DX,PEGASUS HYPER 8, AURORA S, ANDES DX, SUPER ANDES DX, SPACE DX, SEINE DX,SPECIAL GRAVURE DX, PEGASUS, SILVER PEGASUS, PEGASUS HARMONY, GREENLANDDX100, SUPER GREENLAND DX100, <SSS> ENERGY SOFT, <SSS> ENERGY LIGHT andEE HENRY (produced by Nippon Paper Group, Inc.); KANT EXCEL, EXCEL SUPERB, EXCEL SUPER C, KANT EXCEL BARU, UTRILLO EXCEL, HEINE EXCEL and DANTEEXCEL (produced by Daio Paper Corporation); COSMO ACE (produced byNippon Daishowa Paperboard Co., Ltd.); SEMI-UPPER L, HIGH BETA, HIGHGAMMA, SHIROMARI L, HUMMING, WHITE HUMMING, SEMI-UPPER HIL and SHIROMARIHIL (produced by Hokuetsu Paper Mills, Ltd.); RUBY LIGHT HREW, PEARLSOFT and RUBY LIGHT H (produced by Mitsubishi Paper Mills Limited);Shaton, Ariso and Smash (produced by Chuetsu Pulp & Paper Co., Ltd.);and Star Chemy and Chemy Super (produced by Marusumi Paper Co., Ltd.).

As seen in many documents, a coat layer of ordinary commercial printingpaper is formulated so as to contain a binder (resin, emulsion, starch,etc.) by approximately 10 parts by mass to 15 parts by mass per 100parts by mass of an inorganic pigment (kaolin, calcium carbonate, etc.).Here, when the manner in which the pigment is present in the coat layer,and further, the concentration gradient of the pigment in the coat layerare taken into consideration, the following can be regarded as possible:(1) formation of a clear layer or the like on the outermost surface of acoating film, as often seen in the case of paint, etc.; (2) penetrationof binder components into original paper, which may cause the upper andlower layers to have asymmetrical concentration distributions. As to(1), it has been found that matters related to (1) are scarcelydiscussed in documents (documents concerning the glossiness, etc. ofcoated paper) in the relevant field. It is inferred that since the ratioof resin to other components in the coat layer is lower than the ratioof resin to other components in ordinary paint or the like, and theamount of the resin in the coat layer is not large enough for the resinto be deposited on the surface, anything like a clear layer does noteasily form.

In meetings aimed at exchanging technical opinions with experts engagedin producing commercial coated paper, many of them are found to have atechnological concept that a binder should have a function of providingstrength to such an extent that a layer can be prevented from peelingoff at the time of printing or particles can be prevented from detachingat the time of cutting; also, perhaps the production of coated paper isliable to become troublesome, as the amount of resin increases;accordingly, in the case of this type of paper, some hope to add abinder as little as possible.

As to (2), it is actually said that as the resin in the coating solutionpenetrates into the original paper, there arises a phenomenon in whichthe proportion of the resin in a coating layer becomes lower (than theproportion of the resin in the coating solution) or a layer is formed atthe interface between the coating layer and the original paper; however,an example of creation of a gradient in the layer itself has not yetbeen confirmed (even in documents). Nevertheless, formation of aresin-rich layer at the interface between the coating layer and theoriginal paper is possible, in which case lower parts of the layer havehigher resin concentrations.

Examples of the method for polishing the outermost layer of the coatedpaper include, but are not limited to, a method of polishing with theuse of sandpaper or wrapping paper, a method of polishing with the useof a wire brush, a method of polishing with the use of a polishingroller or an endless polishing belt, and a method of polishing with theuse of a sandblast.

In producing the coated paper, the polishing may be carried out byarbitrarily providing a polishing process immediately after drying,before or after calendering, or in a process subsequent to coating, suchas a slit process or packing process; alternatively, a user may carryout the polishing before printing, using a polishing device. Also, thepolishing device may be installed in a printer so as to performpolishing each time printing is conducted.

As to the polishing, the whole surface of paper may be polished, or onlyan area to be subjected to ink-jet printing may be selectively polished.

For instance, the following paper usage is possible: the above-mentionedordinary printing paper is subjected to offset printing or gravureprinting in advance, then only an area which requires ink-jet printingis polished, and the area is printed with images, letters/characters,etc.

According to this method, hybrid printing, which has conventionally beenperformed using paper suitable for both ink-jet printing and ordinaryprinting, can also be performed using the above-mentioned ordinaryprinting paper, and thus it becomes possible for ordinary printing andink-jet printing to employ paper in common. Also, this method enablesprinting of an address, etc. by ink-jet printing, which has been deemeddifficult to achieve in ordinary printing.

Additionally, the polishing device may be installed in a unit of theprinter, or may be independently prepared as a separate unit.

Specially made coated paper can be substituted for the medium of thepresent invention, as long as it satisfies the requirements of thepresent invention. In particular, coated paper in which the airpermeability of a coat layer itself is high can be used. Examples of thecoated paper in which the air permeability of a coat layer is highinclude some coated paper for electronic photographs, and coated paperfor gravure printing. Specific examples thereof include POD GLOSS COAT(produced by Oji paper Co., Ltd.), FL GRAVURE (produced by Nippon PaperGroup, Inc.), and ACE (produced by Nippon Paper Group, Inc.). Theseproducts include coat layers having large numbers of pores, and so anyof these products can be used as the medium including the barrier layerof the present invention.

The ink included in the ink media set of the present invention can besuitably used for printers equipped with ink-jet heads of any type,including the piezo type in which ink droplets are ejected by deforminga diaphragm that forms a wall surface of an ink flow path, with the useof a piezoelectric element as a pressure generating unit thatpressurizes ink in the ink flow path, and thusly changing the volume ofthe ink flow path (refer to JP-A No. 02-51734); the thermal type inwhich bubbles are generated by heating ink in an ink flow path with theuse of an exothermic resistive element (refer to JP-A No. 61-59911); andthe electrostatic type in which ink droplets are ejected by placing adiaphragm and an electrode, which form a wall surface of an ink flowpath, to face each other, then deforming the diaphragm by electrostaticforce generated between the diaphragm and the electrode, and thuslychanging the volume of the ink flow path (refer to JP-A No. 06-71882).

As described above, the recording medium in the ink media set is used incombination with the ink in the ink media set. The combination of therecording medium and the ink can be suitably used in various fields,notably in image recording apparatuses (printers) based upon ink-jetrecording; for instance, the combination of the recording medium and theink can be particularly suitably used for an ink cartridge, ink recordedmatter, an ink-jet recording apparatus and an ink-jet recording methodof the present invention described below.

(Ink Cartridge)

An ink cartridge of the present invention includes a container to housethe ink included in the ink media set of the present invention, andfurther includes other members, etc. suitably selected in accordancewith the necessity.

The container is not particularly limited, and the shape, structure,size, material and the like thereof may be suitably selected inaccordance with the intended use. Suitable examples thereof include acontainer having an ink bag or the like formed of an aluminum laminatedfilm, resin film, etc.

Next, the ink cartridge will be explained with reference to FIGS. 1 and2. Here, FIG. 1 is a diagram showing one example of the ink cartridge ofthe present invention, and FIG. 2 is a diagram exemplarily showing theink cartridge of FIG. 1 with the inclusion of a case (outer covering).

In respect of an ink cartridge (200), as shown in FIG. 1, the ink of thepresent invention is supplied from an ink inlet (242) into an ink bag(241), and the ink inlet (242) is closed by means of fusion bondingafter air is discharged. When the ink cartridge is used, an ink ejectionoutlet (243) made of a rubber material is pricked with a needle of anapparatus main body, and the ink is thus supplied to the apparatus.

The ink bag (241) is formed of an air-impermeable packing material suchas an aluminum laminated film. As shown in FIG. 2, this ink bag (241) isnormally housed in a plastic cartridge case (244) and detachably mountedon a variety of ink-jet recording apparatuses.

The ink cartridge of the present invention houses the ink included inthe ink media set of the present invention and can be detachably mountedon a variety of ink-jet recording apparatuses. It is particularlydesirable that the ink cartridge be detachably mounted on an ink-jetrecording apparatus of the present invention described below.

(Ink-Jet Recording Method and Ink-Jet Recording Apparatus)

An ink-jet recording apparatus of the present invention includes atleast an ink jetting unit, and further includes other units suitablyselected in accordance with the necessity, such as a stimulus generatingunit and a controlling unit.

An ink-jet recording method of the present invention includes at leastan ink jetting step, and further includes other steps suitably selectedin accordance with the necessity, such as a stimulus generating step anda controlling step.

The ink-jet recording method of the present invention can be suitablyperformed by the ink-jet recording apparatus of the present invention,and the ink jetting step can be suitably performed by the ink jettingunit. Also, the other steps can be suitably performed by the otherunits.

The ink jetting step is a step of jetting the ink included in the inkmedia set of the present invention so as to record an image on therecording medium included in the ink media set, by applying a stimulusto the ink.

The ink jetting unit is a unit configured to jet the ink included in theink media set of the present invention so as to record an image on therecording medium included in the ink media set, by applying a stimulusto the ink. The ink jetting unit is not particularly limited, andexamples thereof include nozzles for ejecting ink.

In the present invention, at least part of a liquid chamber, a fluidresistance unit, a diaphragm and a nozzle member of an ink-jet head ispreferably formed of a material containing at least either silicone ornickel.

Also, the diameter of the ink-jet nozzle is preferably 30 μm or less,more preferably 1 μm to 20 μm.

Additionally, sub-tanks for supplying ink onto the ink-jet head arepreferably provided such that the sub-tanks are replenished with inkfrom the ink cartridge via a supply tube.

Further, in the ink-jet recording method of the present invention, themaximum amount of the ink attached onto the recording medium ispreferably 8 g/m² to 20 g/m² at a resolution of 300 dpi or higher.

The stimulus can, for example, be generated by the stimulus generatingunit, and the stimulus is not particularly limited and may be suitablyselected in accordance with the intended use. Examples thereof includeheat, pressure, vibration and light. Each of these may be used alone orin combination with two or more. Among these, heat and pressure aresuitable.

Examples of the stimulus generating unit include heaters, pressurizers,piezoelectric elements, vibration generators, ultrasonic oscillators andlights. Specific examples thereof include a piezoelectric actuator suchas a piezoelectric element, a thermal actuator that uses athermoelectric conversion element such as an exothermic resistiveelement and utilizes phase change caused by film boiling of a liquid, ashape-memory-alloy actuator that utilizes metal phase change caused bytemperature change, and an electrostatic actuator that utilizeselectrostatic force.

The manner in which the ink included in the ink media set jets is notparticularly limited and varies according to the type or the like of thestimulus. In the case where the stimulus is “heat”, there is, forexample, a method in which thermal energy corresponding to a recordingsignal is given to the ink in a recording head, using a thermal head orthe like, bubbles are generated in the ink by the thermal energy, andthe ink is ejected as droplets from nozzle holes of the recording headby the pressure of the bubbles. Meanwhile, in the case where thestimulus is “pressure”, there is, for example, a method in which byapplying voltage to a piezoelectric element bonded to a site called apressure chamber that lies in an ink flow path in a recording head, thepiezoelectric element bends, the volume of the pressure chamberdecreases, and thus the ink is ejected as droplets from nozzle holes ofthe recording head.

It is desirable that the ink droplets jetted be, for example, 1 pl to 40pl in size, 5 m/s to 20 m/s in ejection velocity, 1 kHz or greater indrive frequency and 300 dpi or greater in resolution.

The controlling unit is not particularly limited and may be suitablyselected in accordance with the intended use, as long as it can controloperations of the aforementioned units. Examples thereof includeapparatuses such as a sequencer and a computer.

One aspect of performing the ink-jet recording method of the presentinvention by the ink-jet recording apparatus of the present inventionwill be explained with reference to the drawings. The ink-jet recordingapparatus in FIG. 3 includes an apparatus main body (101), a paper feedtray (102) for feeding paper that is loaded thereon into the apparatusmain body (101), a paper discharge tray (103) for storing paper whichhas been loaded into the apparatus main body (101) and on which imageshave been recorded (formed), an ink cartridge loading section (104), anupper cover (111) which covers the upper surface side of the apparatusmain body (101), and a front surface (112) which supports the uppercover (111), at the front side of the apparatus main body (101). Anoperation unit (105) composed of operation keys, a display and the likeis placed on the upper surface of the ink cartridge loading section(104). The ink cartridge loading section (104) has a front cover (115)capable of opening and closing to attach and detach an ink cartridge(200).

In the apparatus main body (101), as shown in FIGS. 4 and 5, a carriage(133) is freely slidably held in the main scanning direction by a guiderod (131), which is a guide member laterally passed between left andright side plates (not shown), and a stay (132); and the carriage (133)is moved for scanning in the direction indicated by the arrow A in FIG.5 by a main scanning motor (not shown). The belt moves in the directionindicated by the arrow B in FIG. 5 to convey paper.

A recording head (134) composed of four ink-jet recording heads whicheject ink droplets of yellow (Y), cyan (C), magenta (M) and black (Bk)is installed in the carriage (133) such that a plurality of ink ejectionoutlets are aligned in the direction intersecting the main scanningdirection and that the ink droplet ejection direction faces downward.

For each of the ink-jet recording heads composing the recording head134, it is possible to use, for example, a head provided with any of thefollowing actuators as a energy-generating unit for ejecting ink: apiezoelectric actuator such as a piezoelectric element, a thermalactuator that uses a thermoelectric conversion element such as anexothermic resistive element and utilizes phase change caused by filmboiling of a liquid, a shape-memory-alloy actuator that utilizes metalphase change caused by temperature change, and an electrostatic actuatorthat utilizes electrostatic force.

Also, the carriage (133) incorporates sub-tanks (135) of each color forsupplying inks of each color to the recording head (134). Each sub-tank(135) is supplied and replenished with the ink included in the ink mediaset of the present invention from the ink cartridge (200) of the presentinvention loaded into the ink cartridge loading section (104), via anink supply tube (not shown).

Meanwhile, as a paper feed unit for feeding sheets of paper (142) loadedon a paper loading section (pressure plate) (141) of the paper feed tray(102), there are provided a half-moon roller (paper feed roller (143))which feeds the sheets of paper (142) one by one from the paper loadingsection (141), and a separation pad (144) which faces the paper feedroller (143) and is formed of a material with a large frictioncoefficient. This separation pad (144) is biased toward the paper feedroller (143) side.

As a conveyance unit for conveying the paper (142), which has been fedfrom this paper feed unit, under the recording head (134), there areprovided a conveyance belt (151) for conveying the paper (142) by meansof electrostatic adsorption; a counter roller (152) for conveying thepaper (142), which is sent from the paper feed unit via a guide (145),such that the paper (142) is sandwiched between the counter roller (152)and the conveyance belt (151); a conveyance guide (153) for making thepaper (142), which is sent upward in the substantially verticaldirection, change its direction by approximately 90° and thuslycorrespond with the conveyance belt (151); and an end pressurizingroller (155) biased toward the conveyance belt (151) side by a pressingmember (154). Also, there is provided a charging roller (156) as acharging unit for charging the surface of the conveyance belt (151).

The conveyance belt (151) is an endless belt and is capable of moving incircles in the belt conveyance direction, passed between a conveyanceroller (157) and a tension roller (158). The conveyance belt (151) has,for example, a surface layer serving as a paper adsorbing surface, thatis formed of a resinous material such as an ethylene-tetrafluoroethylenecopolymer (ETFE) having a thickness of approximately 40 μm for whichresistance control has not been conducted, and a back layer(intermediate resistance layer, ground layer) that is formed of the samematerial as this surface layer, for which resistance control has beenconducted using carbon. On the back of the conveyance belt (151), aguide member (161) is placed correspondingly to a region where printingis carried out by the recording head (134). Additionally, as a paperdischarge unit for discharging the paper (142) on which images or thelike have been recorded by the recording head (134), there are provideda separation pawl (171) for separating the paper (142) from theconveyance belt (151), a paper discharge roller (172) and a paperdischarge small roller (173), with the paper discharge tray (103) beingplaced below the paper discharge roller (172).

A double-sided paper feed unit (181) is mounted on a rear surfaceportion of the apparatus main body (101) in a freely detachable manner.The double-sided paper feed unit (181) takes in the paper (142) returnedby rotation of the conveyance belt (151) in the opposite direction andreverses it, then refeeds it between the counter roller (152) and theconveyance belt (151). Additionally, a manual paper feed unit (182) isprovided on an upper surface of the double-sided paper feed unit (181).

In this ink-jet recording apparatus, the sheets of paper (142) are fedone by one from the paper feed unit, and the paper (142) fed upward inthe substantially vertical direction is guided by the guide (145) andconveyed between the conveyance belt (151) and the counter roller (152).Further, the conveyance direction of the paper (142) is changed byapproximately 90°, as an end of the paper (142) is guided by theconveyance guide (153) and pressed onto the conveyance belt (151) by theend pressurizing roller (155).

On this occasion, the conveyance belt (151) is charged by the chargingroller (156), and the paper (142) is electrostatically adsorbed onto theconveyance belt (151) and thusly conveyed. Here, by driving therecording head (134) according to an image signal while moving thecarriage (133), ink droplets are ejected onto the paper (142) havingstopped so as to carry out recording for one line, and after the paper(142) is conveyed by a predetermined distance, recording for the nextline is carried out. On receipt of a recording completion signal or sucha signal as indicates that the rear end of the paper (142) has reachedthe recording region, recording operation is finished, and the paper(142) is discharged onto the paper discharge tray (103).

Once the amount of ink remaining in the sub-tanks (135) has beendetected as too small, a required amount of ink is supplied from the inkcartridge (200) into the sub-tanks (135).

As to this ink-jet recording apparatus, when ink in the ink cartridge(200) of the present invention has been used up, it is possible toreplace only an ink bag inside the ink cartridge (200) by dismantlingthe housing of the ink cartridge (200). Also, even when the inkcartridge (200) is longitudinally placed and employs a front-loadingstructure, it is possible to supply ink stably. Therefore, even when theapparatus main body (101) is installed to with little space over it, forexample when the apparatus main body (101) is stored in a rack or whenan object is placed over the apparatus main body (101), it is possibleto replace the ink cartridge (200) with ease.

It should be noted that although the ink-jet recording method of thepresent invention has been explained referring to an example in which itis applied to a serial-type (shuttle-type) ink-jet recording apparatuswhere a carriage performs scanning, the ink-jet recording method of thepresent invention can also be applied to line-type ink-jet recordingapparatuses provided with line-type heads.

Also, the ink-jet recording apparatus and the ink-jet recording methodof the present invention can be applied to a variety of types ofrecording based upon ink-jet recording systems. For example, they can beparticularly suitably applied to ink-jet recording printers, facsimileapparatuses, copiers, printer/fax/copier complex machines, and so forth.

The following explains an ink-jet head to which the present invention isapplied.

FIG. 6 is an enlarged view showing elements of an ink-jet head to whichthe present invention has been applied, and FIG. 7 is an enlargedcross-sectional view showing main parts of the ink-jet head with respectto the channel-to-channel direction.

This ink-jet head is composed of a frame (10) provided with an inksupply port (not shown) (which supplies ink in the direction from thesurface toward the back in FIG. 6 (toward the back surface of paper))and an indentation serving as a common liquid chamber (12); a flow pathplate (20) including a fluid resistance section (21), an indentationserving as a pressurized liquid chamber (22), and a communicating port(23) communicated with a nozzle (31); a nozzle plate (30) forming thenozzle (31); a diaphragm (60) provided with a diaphragm protrusion (61),a diaphragm part (62) and an ink flow-in port (63); a laminatedpiezoelectric element (50) joined to the diaphragm (60) with an adhesivelayer (70) placed in between; and a base (40) on which the laminatedpiezoelectric element (50) is fixed. The base (40) is made of a bariumtitanate-based ceramic and joined to the laminated piezoelectric element(50) that is arranged in two rows.

In the laminated piezoelectric element (50), piezoelectric layers (51),which are formed of lead zirconate titanate (PZT) and each one of whichis 10 μm to 50 μm in thickness, and internal electrode layers (52),which are formed of silver-palladium (AgPd) and each one of which isseveral micrometers in thickness, are alternately deposited on top ofone another. The internal electrode layers (52) are connected toexternal electrodes (53), at their ends on both sides.

The laminated piezoelectric element (50) is formed into the shape ofcomb teeth by half-cut dicing, in which drive parts (movable parts) (56)and support parts (non-drive parts) (57) are alternately disposed (FIG.7).

The length of the outer end of one of the two external electrodes (53)(which is contiguous to the ends of the internal electrode layers (52)on one side in the direction of the surface or the back in FIG. 6 (theback surface of paper)) is limited by cutting or the like so as to bedivided by half-cut dicing, and divided pieces serve as individualelectrodes (54). The other of the two external electrodes (53) is notdivided by dicing but electrically continuous, serving as a commonelectrode (55).

An FPC (80) is welded to the individual electrodes (54) of the driveparts. With an electrode layer provided at an end of the laminatedpiezoelectric element, the common electrode (55) is joined to a Gndelectrode of the FPC (80) in a twisted manner. On the FPC (80), a driverIC (not shown) is mounted, which controls application of drive voltageto the drive parts (movable parts) (56).

The diaphragm (60) is equipped with the diaphragm part (62) formed as athin film; the island-like convex portion (island part) (61) which isformed at the center of this diaphragm part (62) and joined to the driveparts (movable parts) (56) of the laminated piezoelectric element (50);a thick film portion including a beam joined to the support parts (notshown); and an opening serving as the ink flow-in port (63), formed bycombining two Ni-plated films produced by electroforming. The diaphragmportion has a thickness of 3 μm and a width of 35 μm (with respect toone side).

By patterning the adhesive layer (70) including a gap material, theisland-like diaphragm protrusion (61) of the diaphragm (60) is bonded tothe drive parts (movable parts) (56) of the laminated piezoelectricelement (50), and the diaphragm (60) is bonded to the frame (10).

As to the flow path plate (20), the following members are patterned byetching with the use of a silicon single-crystal substrate: the fluidresistance section (21); the indentation serving as the pressurizedliquid chamber (22); and a through-hole serving as the communicatingport (23), placed in a position corresponding to the nozzle (31).

The portions that remain unetched serve as partitions (24) of thepressurized liquid chamber (22). Additionally, this head is providedwith a portion where the etching width is small to serve as the fluidresistance section (21).

A nozzle plate (30) is formed of a metal material, for example anNi-plated film produced by electroforming, and a large number of nozzles(31), which are minute ejection outlets for jetting ink droplets, areformed therein. The internal shape (inner shape) of each of thesenozzles (31) is similar to the shape of a horn (which may otherwise be asubstantially columnar shape or a substantially conical and trapezoidalshape). Also, the diameter of each of these nozzles (31) isapproximately 20 μm to 35 μm as a diameter on the side where inkdroplets exit. Additionally, the nozzle pitch in each row is 150 dpi.

An ink ejection surface (on the nozzle surface side) of the nozzle plate(30) is provided with an ink-repellent layer (90) and a water-repellentlayer (not shown) which has been subjected to water-repellent surfacetreatment. High image quality is obtained through stabilization of thedroplet shape and jetting properties of ink by providing awater-repellent film selected in accordance with the ink properties,which is produced by PTFE-Ni eutectoid plating, electrodeposition of afluorine resin, vapor deposition coating of an evaporable fluorine resin(such as a fluorinated pitch), baking of a silicone resin and a fluorineresin after application of solvent, etc. For instance, as to thefluorine resin among these, although a variety of materials are known asfluorine resins, superior water repellency can be obtained by subjectinga modified perfluoropolyoxetane (product name: OPTOOL DSX, produced byDaikin Industries, Ltd.) to vapor deposition so as to have a thicknessof 30 Å to 100 Å.

The frame (10) including the ink supply port and the indentation servingas the common liquid chamber (12) is produced by molding a resin.

As to the ink-jet head with such a structure, by applying a drivewaveform (a pulse voltage of 10V to 50V) to the drive parts (movableparts) (56) correspondingly to a recording signal, displacement of thelamination direction is generated in the drive parts (movable parts)(56), there is an increase in pressure as the pressurized liquid chamber(22) is pressurized, and thus ink droplets are ejected from the nozzle(31) formed in the nozzle plate (30).

Thereafter, once ejection of ink droplets is over, the ink pressure inthe pressurized liquid chamber (22) lowers, and negative pressure isgenerated in the pressurized liquid chamber (22) due to inertia of theflow of ink and a drive pulse discharge process, which is followed by anink supply step. On this occasion, the ink supplied from an ink tankflows into the common liquid chamber (12), passes from the common liquidchamber (12) through the fluid resistance section (21) via the inkflow-in port (63) and then is supplied into the pressurized liquidchamber (22).

The fluid resistance section (21) is effective in reducing residualpressure vibrations after ink ejection; conversely, it serves as aresistance to refilling effected by surface tension. By suitablyselecting the fluid resistance section, it becomes possible to balancereduction in residual pressure and refill time and to shorten the timespent in shifting to an ink droplet ejecting operation that follows (thedriving cycle).

EXAMPLES

The following explains Examples of the present invention; however, itshould be noted that the present invention is not confined to theseExamples in any way.

Preparation Example 1 Surface-Treated Carbon Black Pigment (P1)Dispersion Solution

Into 3,000 mL of 2.5N sodium sulfate solution, 90 g of carbon blackhaving a CTAB specific surface area of 150 m²/g and a DBP oil absorptionof 100 mL/100 g was added, then the mixture was stirred at a temperatureof 60° C. and a rotational speed of 300 rpm and subjected to reactionfor 10 hr, and the carbon black was thus oxidized. This reactionsolution was filtered, then the carbon black which had been filtered outwas neutralized with a sodium hydroxide solution and subjected toultrafiltration.

The carbon black obtained was washed with water and dried, thendispersed into purified water such that its amount was 20% by mass.

Preparation Example 2 Surface-Treated Yellow Pigment (P1) DispersionSolution

As a yellow pigment, a pigment (P1) was produced by plasma-treating C.I. Pigment Yellow 128 at a low temperature and introducing a carboxylicacid group. This pigment (P1) was dispersed into ion-exchange water,then the solution was demineralized and condensed using anultrafiltration membrane, and a yellow pigment dispersion solutionhaving a pigment concentration of 15% was thus obtained.

Preparation Example 3 Surface-Treated Magenta Pigment (P1) DispersionSolution)

A surface-modified magenta pigment (P1) was prepared in accordance withthe procedure of Preparation Example 2, using Pigment Red 122 instead ofC. I. Pigment Yellow 128. As in the above-mentioned example, asurface-modified coloring pigment (P1) obtained was easily dispersed inan aqueous medium when stirred, then the solution was demineralized andcondensed using an ultrafiltration membrane, and a magenta pigment (P1)dispersion solution having a pigment concentration of 15% was thusobtained.

Preparation Example 4 Surface-Treated Cyan Pigment (P1) DispersionSolution

A surface-modified cyan pigment (P1) was prepared in accordance with theprocedure of Preparation Example 2, using C. I. Pigment Cyan 15:3instead of C. I. Pigment Yellow 128. As in the above-mentioned example,a surface-modified coloring pigment (P1) obtained was easily dispersedin an aqueous medium when stirred, then the solution was demineralizedand condensed using an ultrafiltration membrane, and a cyan pigment (P1)dispersion solution having a pigment concentration of 15% was thusobtained.

Synthesis Example 1 Preparation of Polymer Dispersion Solution

The atmosphere inside a 1 L flask equipped with a mechanical stirrer, athermometer, a nitrogen gas introducing pipe, a reflux condenser and adripping funnel was adequately replaced by nitrogen gas, then 11.2 g ofstyrene, 2.8 g of acrylic acid, 12.0 g of lauryl methacrylate, 4.0 g ofpolyethylene glycol methacrylate, 4.0 g of a styrene macromer (productname: AS-6 produced by Toagosei Co., Ltd.) and 0.4 g of mercaptoethanolwere placed, and the temperature was raised to 65° C. Next, a mixedsolution of 100.8 g of styrene, 25.2 g of acrylic acid, 108.0 g oflauryl methacrylate, 36.0 g of polyethylene glycol methacrylate, 60.0 gof hydroxyethyl methacrylate, 36.0 g of a styrene macromer (productname: AS-6 produced by Toagosei Co., Ltd.), 3.6 g of mercaptoethanol,2.4 g of azobisdimethylvaleronitrile and 18 g of methyl ethyl ketone waspoured dropwise into the flask in 2.5 hr. After the dropping of themixed solution had finished, a mixed solution of 0.8 g ofazobisdimethylvaleronitrile and 18 g of methyl ethyl ketone was applieddropwise into the flask in 0.5 hr. The ingredients were aged at 65° C.for 1 hr, then 0.8 g of azobismethylvaleronitrile was added, andfurther, the ingredients were aged for 1 hr. After reaction hadfinished, 364 g to of methyl ethyl ketone was added into the flask, and800 g of a polymer solution having a solid content concentration of 50%by mass was thus obtained.

Preparation Example 5 Preparation of Fine Polymer Particle DispersionContaining Phthalocyanine Pigment (P1)

After sufficiently stirring 28 g of the polymer solution produced inSynthesis Example 1, 26 g of a phthalocyanine pigment (P1), 13.6 g of 1mol/L potassium hydroxide solution, 20 g of methyl ethyl ketone and 30 gof ion-exchange water, the ingredients were kneaded using a three-rollmill. The paste obtained was put into 200 g of ion-exchange water, andthe solution was sufficiently stirred; thereafter, the methyl ethylketone and the water were removed by distillation using an evaporator,and a cyan fine polymer particle dispersion was thus obtained.

Preparation Example 6 Preparation of Fine Polymer Particle DispersionContaining Dimethyl Quinacridone Pigment (P1)

A magenta fine polymer particle dispersion was obtained in a mannersimilar to Preparation Example 5, except that the phthalocyanine pigment(P1) was changed to Pigment Red 122.

Preparation Example 7 Preparation of Fine Polymer Particle DispersionContaining Monoazo Yellow Pigment (P1)

A yellow fine polymer particle dispersion was obtained in a mannersimilar to Preparation Example 5, except that the phthalocyanine pigment(P1) was changed to Pigment Yellow 74.

Preparation Example 8 Preparation of Fine Polymer Particle DispersionContaining Carbon Black Pigment (P1)

A black fine polymer particle dispersion was obtained in a mannersimilar to Preparation Example 5, except that the phthalocyanine pigment(P1) was changed to carbon black.

Preparation Example 9 Preparation of Phthalocyanine Pigment (P1)Dispersion

A mixture was prepared by mixing 150 g of C. I. Pigment Cyan 15:3, 110 gof a polyoxyethylene β-naphthyl ether as a pigment dispersantrepresented by Structural Formula (2) shown below (R: alkyl group, m=4,n=40), 2 g of Pionin A-51-B (produced by Takemoto Oil & Fat Co., Ltd.)and 738 g of distilled water, then this mixture was predispersed andsubsequently dispersed in a circulated manner for 20 hr using adisc-type bead mill (Model KDL, manufactured by Shinmaru EnterprisesCorporation; media: 0.3 mmφ zirconia balls), and a phthalocyaninepigment (P1) dispersion was thus obtained.

(In Structural Formula (2), R denotes an alkyl group having 1 to 20carbon atoms, m denotes an integer of 0 to 7, and n denotes an integerof 20 to 200.)

Preparation Example 10 Preparation of Dimethyl Quinacridone Pigment (P1)Dispersion

A dimethyl quinacridone pigment (P1) dispersion was obtained in a mannersimilar to Preparation Example 9, except that the C. I. Pigment Cyan15:3 was changed to C. I. Pigment Red 122.

Preparation Example 11 Preparation of Monoazo Yellow Pigment (P1)Dispersion

A monoazo yellow pigment (P1) dispersion was obtained in a mannersimilar to Preparation Example 9, except that the C. I. Pigment Cyan15:3 was changed to C. I. Pigment Yellow 74.

The following shows a synthesis example of an acrylic-silicone resinemulsion among components able to be contained in the water-dispersibleresin (A) used in the present invention.

Synthesis Example 2 Synthesis 1 of Silicone-Modified Acrylic Resin FineParticles not Containing Reactive Silyl Group

The atmosphere inside a flask equipped with a mechanical stirrer, athermometer, a nitrogen gas introducing pipe, a reflux condenser and adripping funnel was adequately replaced by nitrogen gas, then 10 g ofAQUALON RN-20 (produced by Dai-Ichi Kogyo Seiyaku Co., Ltd.), 1 g ofpotassium persulfate and 286 g of purified water were placed, and thetemperature was raised to 65° C. Next, a mixed solution containing 150 gof methyl methacrylate, 100 g of 2-ethylhexyl acrylate, 20 g of acrylicacid, 20 g of vinyltriethoxysilane, 10 g of AQUALON RN-20 (produced byDai-Ichi Kogyo Seiyaku Co., Ltd.), 4 g of potassium persulfate and 398.3g of purified water was poured dropwise into the flask in 2.5 hr. Theingredients were heated and aged at 80° C. for 3 hr then cooled, and thepH was adjusted to 7 to 8, using potassium hydroxide. Finally, ethanolwhich had been formed in the reaction process was evaporated. Theparticle diameter of the resin, measured using MICROTRACK UPA, was 130nm. The minimum film forming temperature (MFT) was 0° C.

Synthesis Example 3 Synthesis 2 of Silicone-Modified Acrylic Resin FineParticles not Containing Reactive Silyl Group

The atmosphere inside a flask equipped with a mechanical stirrer, athermometer, a nitrogen gas introducing pipe, a reflux condenser and adripping funnel was adequately replaced by nitrogen gas, then 10 g ofAQUALON RN-20 (produced by Dai-Ichi Kogyo Seiyaku Co., Ltd.), 1 g ofpotassium persulfate and 286 g of purified water were placed, and thetemperature was raised to 65° C. Next, a mixed solution containing 150 gof methyl methacrylate, 100 g of 2-ethylhexyl acrylate, 20 g of acrylicacid, 40 g of hexyltrimethoxysilane, 10 g of AQUALON RN-20 (produced byDai-Ichi Kogyo Seiyaku Co., Ltd.), 4 g of potassium persulfate and 398.3g of purified water was poured dropwise into the flask in 3 hr. Theingredients were heated and aged at 80° C. for 3 hr then cooled, and thepH was adjusted to 7 to 8, using potassium hydroxide. Finally, ethanolwhich had been formed in the reaction process was evaporated. Theparticle diameter of the resin, measured using MICROTRACK UPA, was 148nm. The minimum film forming temperature (MFT) was 0° C.

Synthesis Example 4 Synthesis of Silicone-Modified Acrylic Resin FineParticles Containing Reactive Silyl Group

Silicone-modified acrylic resin fine particles containing a reactivesilyl group were synthesized in accordance with Examples described inJP-A 06-157861.

The atmosphere inside a flask equipped with a mechanical stirrer, athermometer, a nitrogen gas introducing pipe, a reflux condenser and adripping funnel was adequately replaced by nitrogen gas, then 100 g ofpurified water, 3 g of sodium dodecylbenzenesulfonate and 1 g ofpolyethylene glycol nonylphenyl ether were placed, with the addition of1 g of ammonium persulfate and 0.2 g of sodium hydrogen sulfite, and thetemperature was raised to 60° C. Next, 30 g of butyl acrylate, 40 g ofmethyl methacrylate, 19 g of butyl methacrylate, 10 g ofvinylsilanetriol potassium salt and 1 g of3-methacryloxypropylmethyldimethoxysilane were poured dropwise into theflask in 3 hr. On this occasion, the solution for polymerizationreaction was polymerized, as its pH was adjusted to 7 using ammoniaaqueous solution. The particle diameter of the resin, measured usingMICROTRACK UPA, was 160 nm.

The following explains Examples and Comparative Examples of the presentinvention; however, it should be noted that the present invention is notconfined to these Examples and Comparative Examples. It should also benoted that the amounts of components mentioned in Examples are basedupon mass.

Ink compositions according to the following formulations were prepared,and they were each mixed into a lithium hydroxide 10% aqueous solutionsuch that their pH values became 9. Thereafter, the solutions werefiltered using a membrane filter of 0.8 μm in average pore diameter, andink compositions were thus obtained.

The following explains the present invention more specifically by meansof Ink Production Examples; however, it should be noted that the presentinvention is not confined to these Ink Production Examples. It shouldalso be noted that the amounts (%) of components mentioned below arebased upon mass.

Ink Production Example 1 Black Ink 1

The carbon black produced in Preparation Example 1 9% (as a solidcontent) 3-methyl-1,3-butanediol 20%  Glycerin 15%  2-pyrrolidone 2% Thecompound represented by Structural Formula (1) 1% shown below (R₁: CF₃,Rf: CF₃, x = 2, y = 2, z = 10) 2-ethyl-1,3-hexanediol 2% A total of 100%was made by addition of ion-exchange water. Structural Formula (1)

(In Structural Formula (1), R₁ denotes any one of a hydrogen atom, analkyl group and a fluorine-containing group, Rf denotes afluorine-containing group, and each of x, y and z denotes an integer of1 or greater.)

Ink Production Example 2 Yellow Ink 1

The yellow pigment (P1) dispersion solution produced in 6% (as aPreparation Example 2 solid content) 1,3-butanediol 20% Glycerin 20%2-pyrrolidone 1% The compound represented by Structural Formula (1) 1%shown above (R₁: CF₃, Rf: C₂F₅, x = 2, y = 2, z = 10)2,2,4-trimethyl-1,3-pentanediol 2% A total of 100% was made by additionof ion-exchange water.

Ink Production Example 3 Magenta Ink 1

The magenta pigment (P1) dispersion solution produced 8% (as a inPreparation Example 3 solid content) Triethylene glycol isobutyl ether2% Glycerin 20% The compound represented by Structural Formula (1) 1%shown above (R₁: CF₃, Rf: C₂F₅, x = 2, y = 2, z = 10)2-ethyl-1,3-hexanediol 2% A total of 100% was made by addition ofion-exchange water.

Ink Production Example 4 Cyan Ink 1

The cyan pigment (P1) dispersion solution produced in 6% (as aPreparation Example 4 solid content) 3-methyl-1,3-butanediol 15%Glycerin 15% The compound represented by Structural Formula (1) 1% shownabove (R₁: H, Rf: C₂F₅, x = 2, y = 2, z = 10) 2-ethyl-1,3-hexanediol 2%A total of 100% was made by addition of ion-exchange water.

Ink Production Example 5 Cyan Ink 2

The cyan pigment (P1) dispersion solution produced in 5% (as aPreparation Example 5  solid content) 1,6-hexanediol  20% Glycerin  15%The compound represented by Structural Formula (1) 1.5% shown above (R₁:CF₃, Rf: C₂F₅, x = 4, y = 4, z = 20) FS-300 (produced by E. I. du Pontde Nemours and 0.3% Company) 2-ethyl-1,3-hexanediol   2% A total of 100%was made by addition of ion-exchange water.

Ink Production Example 6 Magenta Ink 2

The magenta pigment (P1) dispersion solution produced 7.5% (as a inPreparation Example 6 solid content) Dipropylene glycol  15% Glycerin 20% The compound represented by Structural Formula (1) 0.5% shown above(R₁: CF₃, Rf: C₂F₅, x = 4, y = 4, z = 20) FSN-100 (produced by E. I. duPont de Nemours and 0.5% Company) 2-ethyl-1,3-hexanediol   2% A total of100% was made by addition of ion-exchange water.

Ink Production Example 7 Yellow Ink 2

The yellow pigment (P1) dispersion solution produced in 5% (as aPreparation Example 7 solid content) 2-methyl-2,4-pentanediol 10%Glycerin 20% The compound represented by Structural Formula (1) 1.5% shown above (R₁: CF₃, Rf: C₂F₅, x = 4, y = 4, z = 20)2,2,4-trimethyl-1,3-pentanediol  1% A total of 100% was made by additionof ion-exchange water.

Ink Production Example 8 Black Ink 2

The black pigment (P1) dispersion solution produced in 8% (as aPreparation Example 8 solid content) 1,6-hexanediol  20% Glycerin  12%The compound represented by Structural Formula (1) 1.5% shown above (R₁:H, Rf: C₂F₅, x = 4, y = 4, z = 20) 2-ethyl-1,3-hexanediol 2.5% A totalof 100% was made by addition of ion-exchange water.

Comparative Production Example 1 Comparative Pigment (P1) Black Ink 1

A black ink was obtained in a manner similar to Ink

Production Example 1, except that ECTD-3NEX (an anionic surfactant,produced by Nikko Chemicals Co., Ltd.) was used instead of the compoundrepresented by Structural Formula (1) shown above (R₁: CF₃, Rf: CF₃,x=2, y=2, z=10).

Comparative Production Example 2 Comparative Pigment Yellow Ink 1

A yellow ink was obtained in a manner similar to Ink Production Example2, except that ECTD-6NEX (an anionic surfactant, produced by NikkoChemicals Co., Ltd.) was used instead of the compound represented byStructural Formula (1) shown above (R₁: CF₃, Rf: C₂F₅, x=2, y=2, z=10).

Ink Production Example 9 Magenta Ink 3

A magenta ink was obtained in a manner similar to Ink Production Example3, except that DISPANOL TOC (a nonionic surfactant, produced by NipponOil & Fats Co., Ltd.) was used instead of the compound represented byStructural Formula (1) shown above (R₁: CF₃, Rf: C₂F₅, x=2, y=2, z=10).

Ink Production Example 10 Cyan Ink 3

A cyan ink was obtained in a manner similar to Ink Production Example 4,except that DISPANOL TOC (a nonionic surfactant, produced by Nippon Oil& Fats Co., Ltd.) was used instead of the compound represented byStructural Formula (1) shown above (R₁: H, Rf: C₂F₅, x=2, y=2, z=10).

The following explains the ink compositions, as the inks of InkProduction Examples and Comparative Production Examples of the presentinvention are shown in Table 1.

The surface tension and viscosity of each ink are shown in Table 1.

The surface tension of each ink was measured using CBVP-Z manufacturedby Kyowa Interface Science Co., Ltd. The viscosity of each ink wasmeasured using the R-type viscometer RC-500 manufactured by TOKI SANGYOCO., LTD.

TABLE 1 Surface tension Viscocity Ink Production Example Ink (mN/m) (mPa· s) Ink Production Example 1 Black ink 1 26.9 8.85 Ink ProductionExample 2 Yellow ink 1 26.7 9.04 Ink Production Example 3 Magenta ink 125.8 9.13 Ink Production Example 4 Cyan ink 1 25.7 7.34 Ink ProductionExample 5 Cyan ink 2 25.1 8.12 Ink Production Example 6 Magenta ink 226.8 8.65 Ink Production Example 7 Yellow ink 2 26.2 9.07 Ink ProductionExample 8 Black ink 2 26.3 8.02 Comparative Production Comparative 32.28.99 Example 1 pigment black ink 1 Comparative Production Comparative32.7 9.21 Example 2 pigment yellow ink 1 Ink Production Example 9Magenta ink 3 31.1 9.26 Ink Production Example 10 Cyan ink 3 31.3 7.51

Next, ink sets of Examples 1 and 2 and Comparative Example 1 are shownin Table 2.

TABLE 2 Ink set Black ink Cyan ink Magenta ink Yellow ink Example 1 Inkset 1 Production Production Production Production Example 1 Example 4Example 3 Example 2 Example 2 Ink set 2 Production Production ProductionProduction Example 8 Example 5 Example 6 Example 7 ComparativeComparative Comparative Production Production Comparative Example 1 set1 Production Example 10 Example 9 Production Example 1 Example 2

(Printer Used for Printing)

Printing was carried out on sheets of the following plain paper, usingthe printer in FIGS. 3 and 4 explained in detail in the presentinvention.

(Paper Used for Printing)

As paper for the printing test, MY PAPER (produced by NBS Ricoh Co.,Ltd.) was used.

As to a printing pattern, printing was carried out using the inks ofblack, yellow, magenta and cyan of the present invention at a duty of100%.

As to printing conditions, the recording density was 300 dpi, andone-pass printing was employed.

After printed images had been dried, the images were holisticallyexamined for bleeding on boundaries between each two colors combinedtogether, image bleeding and image density by visual observation and bya reflective color spectrophotometric colorimetry densitometer(manufactured by X-Rite, Inc.), and the images were judged in accordancewith the following evaluation criteria.

(1) Clarity of Image (Feathering and Color Bleeding) Evaluation Criteria

A: all sheets of paper exhibited clear printing without bleeding

B: bleeding in the form of beards was seen on some sheets of paper(recycled paper)

C: bleeding in the form of beards was seen on all sheets of paper

D: bleeding arose to such an extent that outlines of letters/characterswere unclear

(2) Image Density

The optical densities of solid image portions of each color afterprinting were measured using X-RITE 932. The evaluation results areshown in Table 3.

TABLE 3 Color Image Feathering bleeding density Example 1 ProductionExample 1 A A 1.36 Production Example 2 A A 0.88 Production Example 3 AA 1.00 Production Example 4 A A 1.07 Example 2 Production Example 5 A A1.10 Production Example 6 A A 1.04 Production Example 7 A A 0.89Production Example 8 A A 1.34 Comparative Comparative C C 1.20 Example 1Production Example 1 Comparative C C 0.69 Production Example 2Production Example 9 B B 0.81 Production Example 10 B B 0.96

Ink Production Example 11 Black Ink 3

The carbon black produced in Preparation Example 1 8% (as a solidcontent) The acrylic-silicone resin emulsion of Synthesis 4% (as aExample 2 solid content) 3-methyl-1,3-butanediol   8% Glycerin  10%2-pyrrolidone   2% The compound represented by Structural Formula (1)0.5% shown above (R₁: CF₃, Rf: C₂F₅, x = 4, y = 4, z = 20)2,2,4-trimethyl-1,3-pentanediol 1.5% A total of 100% was made byaddition of ion-exchange water.

Ink Production Example 12 Yellow Ink 3

The yellow pigment dispersion solution produced in 5% (as a PreparationExample 2 solid content) The acrylic-silicone resin emulsion ofSynthesis 10% (as a Example 2 solid content) 1,3-butanediol 10% Glycerin 10%  2-pyrrolidone 1% The compound represented by StructuralFormula (1) 1% shown above (R₁: CF₃, Rf: C₂F₅, x = 4, y = 4, z = 20)2,2,4-trimethyl-1,3-pentanediol 2% A total of 100% was made by additionof ion-exchange water.

Ink Production Example 13 Magenta Ink 4

The magenta pigment dispersion solution produced in 6% (as a solidPreparation Example 3 content) The acrylic-silicone resin emulsion ofSynthesis 15% (as a solid Example 3 content) Triethylene glycol isobutylether 2% Glycerin 15%  The compound represented by Structural Formula(1) 1% shown above (R₁: CF₃, Rf: C₂F₅, x = 4, y = 4, z = 20)2-ethyl-1,3-hexanediol 2% A total of 100% was made by addition ofion-exchange water.

Ink Production Example 14 Cyan Ink 4

The cyan pigment dispersion solution produced in 4% (as a solidPreparation Example 4 content) The acrylic-silicone resin emulsion ofSynthesis 15% (as a solid Example 4 content) 3-methyl-1,3-butanediol 10%Glycerin 10% The compound represented by Structural Formula (1) 0.5% shown above (R₁: H, Rf: C₂F₅, x = 4, y = 4, z = 20)2-ethyl-1,3-hexanediol  2% A total of 100% was made by addition ofion-exchange water.

Ink Production Example 15 Cyan Ink 5

The cyan pigment dispersion solution produced in 3.5% (as a solidPreparation Example 5 content) The acrylic-silicone resin emulsion ofSynthesis 10% (as a solid Example 2 content) 1,6-hexanediol  20%Glycerin   8% The compound represented by Structural Formula (1) 1.5%shown above (R₁: CF₃, Rf: C₂F₅, x = 4, y = 4, z = 20) FS-300 (producedby E. I. du Pont de Nemours and 0.3% Company) 2-ethyl-1,3-hexanediol  2% A total of 100% was made by addition of ion-exchange water.

Ink Production Example 16 Magenta Ink 5

The magenta pigment dispersion solution produced in 5% (as a solidPreparation Example 6 content) The acrylic-silicone resin emulsion ofSynthesis 10% (as a solid Example 2 content) Dipropylene glycol 15%Glycerin 15% The compound represented by Structural Formula (1) 1.5% shown above (R₁: CF₃, Rf: C₂F₅, x = 4, y = 4, z = 20)2-ethyl-1,3-hexanediol  2% A total of 100% was made by addition ofion-exchange water.

Ink Production Example 17 Yellow Ink 4

The yellow pigment dispersion solution produced in 4% (as a solidPreparation Example 7 content) The acrylic-silicone resin emulsion ofSynthesis 15% (as a solid Example 3 content) 2-methyl-2,4-pentanediol10% Glycerin 10% The compound represented by Structural Formula (1)1.5%  shown above (R₁: CF₃, Rf: C₂F₅, x = 4, y = 4, z = 20)2,2,4-trimethyl-1,3-pentanediol  1% A total of 100% was made by additionof ion-exchange water.

Ink Production Example 18 Black Ink 4

The black pigment dispersion solution produced in 8% (as a solidPreparation Example 8 content) The acrylic-silicone resin emulsion ofSynthesis 12% (as a solid Example 2 content) 1,6-hexanediol  20%Glycerin   8% The compound represented by Structural Formula (1) 1.5%shown above (R₁: H, Rf: C₂F₅, x = 4, y = 4, z = 20)2-ethyl-1,3-hexanediol 2.5% A total of 100% was made by addition ofion-exchange water.

Ink Production Example 19 Cyan Ink 6

The cyan pigment dispersion solution produced in 4% (as a solidPreparation Example 9 content) W-5025 (urethane resin emulsion, produced14% (as a solid by Mitsui Takeda Chemicals, Inc.) content)1,3-butanediol  20% Glycerin   8% The compound represented by StructuralFormula (1) 1.5% shown above (R₁: CF₃, Rf: C₂F₅, x = 3, y = 3, z = 20)2-ethyl-1,3-hexanediol   2% A total of 100% was made by addition ofion-exchange water.

Ink Production Example 20 Magenta Ink 6

The magenta pigment dispersion solution produced in 7% (as a solidPreparation Example 6 content) W-5661 (urethane resin emulsion, producedby Mitsui 10% (as a solid Takeda Chemicals, Inc.) content)1,5-pentanediol 15% Glycerin 15% The compound represented by StructuralFormula (1) 1.5%  shown above (R₁: CF₃, Rf: C₂F₅, x = 3, y = 3, z = 20)2-ethyl-1,3-hexanediol  2% A total of 100% was made by addition ofion-exchange water.

Ink Production Example 21 Yellow Ink 5

The yellow pigment dispersion solution produced in 6% (as a solidPreparation Example 7 content) The acrylic-silicone resin emulsion ofSynthesis 15% (as a solid Example 3 content) 2-methyl-2,4-pentanediol10% Glycerin 10% The compound represented by Structural Formula (1)1.5%  shown above (R₁: CF₃, Rf: C₂F₅, x: 3, y = 3, z = 20)2,2,4-trimethyl-1,3-pentanediol  3% A total of 100% was made by additionof ion-exchange water.

Ink Production Example 22 Black Ink 5

The black pigment dispersion solution produced in 7% (as a solidPreparation Example 1 content) The acrylic-silicone resin emulsion ofSynthesis 14% (as a solid Example 2 content) 1,6-hexanediol  10%Glycerin  10% The compound represented by Structural Formula (1) 1.5%shown above (R₁: H, Rf: C₂F₅, x = 4, y = 4, z = 20)2-ethyl-1,3-hexanediol 2.5% A total of 100% was made by addition ofion-exchange water.

Preparation of Comparative Pigment Ink Production Examples 23 and 24 InkProduction Example 23 Yellow Ink 6

A yellow ink was obtained in a manner similar to Ink Production Example17, except that the acrylic-silicone resin emulsion of Synthesis Example3 was not used.

Ink Production Example 24 Black Ink 6

A black ink was obtained in a manner similar to Ink Production Example18, except that the acrylic-silicone resin emulsion of Synthesis Example2 was not used.

Preparation of Dye Ink Comparative Production Examples 5 to 8

The following components were mixed together and sufficiently stirred soas to dissolve, then the mixtures were filtered under pressure, using amembrane filter (FLUOROPORE FILTER, manufactured by Sumitomo ElectricIndustries, Ltd) having a pore size of 0.45 μm, and a dye ink set wasthus prepared.

Dye Ink Composition:

(Dyes)

Comparative Production Example 5: Yellow; C.I. Direct Yellow 86

Comparative Production Example 6: Cyan; C.I. Direct Blue 199

Comparative Production Example 7: Magenta; C.I. Acid Red 285

Comparative Production Example 8: Black; C.I. Direct Black 154

(Ink Formulation)

Each of the above-mentioned dyes 4% Glycerin 10% Diethylene glycol 5%Tetramethylurea 5% F-470 (produced by Dainippon Ink And Chemicals, 1%Incorporated) A total of 100% was made by addition of ion-exchangewater.

The following explains the ink compositions, as the inks of InkProduction Examples and Comparative Production Examples of the presentinvention are shown in Table 4.

The surface tension and viscosity of each ink, and the mass ratio(A)/(B) of each water-dispersible resin (A) to each colorant (B) areshown in Table 4.

The surface tension of each ink was measured using CBVP-Z manufacturedby Kyowa Interface Science Co., Ltd. The viscosity of each ink wasmeasured using the R-type viscometer RC-500 manufactured by TOKI SANGYOCO., LTD.

TABLE 4 Surface tension Viscosity Ink Production Example Ink (mN/m) (mPa· s) (A)/(B) Ink Production Example 11 Black ink 3 28.7 7.14 0.5 InkProduction Example 12 Yellow ink 3 27.1 8.71 2.0 Ink Production Example13 Magenta ink 4 26.8 8.98 2.5 Ink Production Example 14 Cyan ink 4 27.68.64 3.75 Ink Production Example 15 Cyan ink 5 25.2 8.43 2.86 InkProduction Example 16 Magenta ink 5 26.7 9.12 2.0 Ink Production Example17 Yellow ink 4 26.8 8.69 3.75 Ink Production Example 18 Black ink 427.9 9.07 1.5 Ink Production Example 19 Cyan ink 6 26.6 7.88 3.5 InkProduction Example 20 Magenta ink 6 27.9 8.96 1.73 Ink ProductionExample 21 Yellow ink 5 25.6 9.11 2.5 Ink Production Example 22 Blackink 5 27.4 7.69 2.0 Comparative Production Comparative pigment cyan 26.15.24 0 Example 3 ink 1 Comparative Production Comparative pigment 27.36.59 0 Example 4 magenta ink 1 Ink Production Example 23 Pigment yellowink 6 21.6 5.80 0 Ink Production Example 24 Pigment black ink 6 26.46.89 0 Comparative Production Comparative dye 23.4 3.19 0 Example 5yellow ink Comparative Production Comparative dye 23.4 3.26 0 Example 6cyan ink Comparative Production Comparative dye 23.7 3.42 0 Example 7magenta ink Comparative Production Comparative dye 23.2 3.28 0 Example 8black ink

Next, ink sets of Examples 3 to 9 and Comparative Examples 2 and 3 areshown in Table 5.

TABLE 5 Ink set Black ink Cyan ink Magenta ink Yellow ink Example 3 Inkset 3 Production Production Production Production Example 11 Example 14Example 13 Example 12 Example 4 Ink set 4 Production ProductionProduction Production Example 18 Example 15 Example 16 Example 17Example 5 Ink set 5 Production Production Production Production Example11 Example 19 Example 20 Example 21 Example 6 Ink set 6 ProductionProduction Production Production Example 22 Example 19 Example 16Example 12 Example 7 Ink set 7 Production Production ProductionProduction Example 11 Example 15 Example 16 Example 17 Example 8 Ink set8 Production Production Production Production Example 18 Example 14Example 13 Example 12 Example 9 Ink set 9 Production ProductionProduction Production Example 18 Example 14 Example 20 Example 21Comparative Comparative Comparative Comparative Comparative ComparativeExample 3 set 3 Production Production Production Production Example 8Example 6 Example 7 Example 5

Next, production of original paper (media) will be explained below.

<Production of Original Paper>

(Original Paper Production Example 1)-Production of Support 1-  80% LBKPNBKP  20% Light calcium carbonate (product name: TP-121, produced by 10% OKUTAMA KOGYO CO., LTD.) Aluminum sulfate 1.0% Amphoteric starch(product name: CATO 3210, produced by 1.0% Nippon NSC Ltd.) Neutralrosin sizing agent (product name: NEUSIZE M-10, 0.3% produced by HarimaChemicals, Inc.) Yield improver (product name: NR-11LS, produced by HYMO0.02%  Co., Ltd.)

A 0.3% slurry containing the components shown above was made into paperusing a fourdrinier machine, the paper was subjected to machinecalendering, and a support 1 having a basis weight of 79 g/m² was thusproduced. Additionally, in a size pressing process in the papermakingstep, a starch oxide aqueous solution was applied onto the paper at arate of 1.0 g/m² as a solid content per side.

Paper Example 1

A coating solution having a solid content concentration of 60% wasprepared by adding the following compounds and water to the support 1produced in Original Paper Production Example 1: 70 parts of kaolin (1.6in refractive index, ULTRAWHITE 90 (produced by Engelhard Corporation))as a pigment, in which particles that are 2 μm or less in diameteroccupy 97% of all particles; 30 parts of heavy calcium carbonate (1.6 inrefractive index, CALSHITEC BRILLIANT-15 (produced by Shiraishi KogyoKaisha, Ltd.)) having an average particle diameter of 1.1 μm; 8 parts ofstyrene-butadiene copolymer emulsion as an adhesive, having a glasstransition temperature (Tg) of −5° C.; 1 part of phosphoricacid-esterified starch; and 0.5 parts of calcium stearate as anauxiliary agent.

This coating solution was applied onto both surfaces of the originalpaper using a blade coater such that the coating layer thickness was 1μm per side, and dried with hot air, then the original paper with thiscoating solution was subjected to a supercalendering process, and“recording paper 1” of the present invention was thus obtained.

Printing was carried out on sheets of this recording paper 1 as arecording medium at an image resolution of 600 dpi, with the inkcompositions and the ink sets shown in Tables 1 and 2, using a 300 dpidrop on-demand experimental printer having nozzles with a nozzleresolution of 384. The amount of ink attached onto the recording paper 1was controlled, as the maximum droplet size was set at 18 μl and thetotal amount of a secondary color was limited to 140%. When solid imagesand letters/characters were printed on a sheet of the recording paper 1,the total amount of ink attached thereto was controlled so as not toexceed 15 g/m² per area of 300 dots×300 dots. The quality andreliability of the images obtained were evaluated. The results are shownin Table 3. Those evaluated as D are not suitable as ink-jet images.

Paper Example 2

Ink-jet recording was carried out in a manner similar to Paper Example1, except that the coating layer thickness was changed to 10 μm per sideand “recording paper 2” was thus obtained.

Paper Example 3

Ink-jet recording was carried out in a manner similar to Paper Example2, except that the inorganic pigment contained in the coating solutionwas changed to 100 parts (as a solid content) of TA-100 (anatase-typetitanium oxide, 2.5 in refractive index, produced by Fuji TitaniumIndustry Co., Ltd.) and “recording paper 3” was thus obtained.

Paper Example 4

Inkjet recording was carried out in a manner similar to Paper Example 1,except that the inorganic pigment contained in the coating solution waschanged to 100 parts of TP-221 (light calcium carbonate, 1.6 (1.59) inrefractive index, produced by OKUTAMA KOGYO CO., LTD.), the coatinglayer thickness was changed to 5 μm per side and “recording paper 4” wasthus obtained.

Paper Example 5

Ink-jet recording was carried out in a manner similar to Paper Example1, except that the coated paper SPACE DX for gravure printing (whichcontains kaolin (1.6 in refractive index) and calcium carbonate (1.6 inrefractive index); produced by Nippon Paper Group, Inc.) was used (as“recording paper 5”) for the recording medium.

Paper Example 6

Ink-jet recording was carried out in a manner similar to Paper Example1, except that the coated paper POD GLOSS for electronic photographs(which contains kaolin (1.6 in refractive index) and calcium carbonate(1.6 in refractive index); produced by Oji paper Co., Ltd.) was used (as“recording paper 6”) for the recording medium.

Paper Example 7

Ink-jet recording was carried out in a manner similar to Paper Example6, except that the surface of the coated paper POD GLOSS for electronicphotographs (which contains kaolin (1.6 in refractive index) and calciumcarbonate (1.6 in refractive index); produced by Oji paper Co., Ltd.)was polished 20 times with wrapping paper such that the coating layerthickness was 5.1 μm per side, and this paper was used (as “recordingpaper 7”) for the recording medium.

As to the media of Paper Examples 1 to 7, as a result of binarizing theobservation images with the use of FE-SEM S-4200 manufactured byHitachi, Ltd., it was confirmed that pores were 1 μm or less indiameter, the pores occupied 40% or less of the media surface in area,which was measured based upon the areas of pores that occupied theimages, and thus all these Paper Examples satisfied the requirementsconcerning the pores in the barrier layers.

The following explains the evaluation items and evaluation methodsconcerning Examples and Comparative Examples shown in Table 5.

(Evaluation Item and Measuring Method Therefor)

(1) Image Quality

1. Ink Strike-Through

Portions of sheets of paper on the opposite side to green solid imageportions of Examples and Comparative Examples were measured for imagedensity, and the values obtained by subtracting the densities ofbackground portions from the respective image densities were defined asink strike-through densities. The images were evaluated in accordancewith the following evaluation criteria, utilizing these inkstrike-through densities and judgment based upon visual observation.

[Evaluation Criteria]

A: the ink strike-through density was 0.1 or less, and uniform printingwas yielded without even causing minor ink strike-through

B: the ink strike-through density was 0.15 or less, and uniform printingwas yielded without even causing minor ink strike-through

C: the ink strike-through density was 0.15 or less, but occurrence ofminor ink strike-through was confirmed

D: occurrence of serious ink strike-through was confirmed

2. Beading

Green solid image portions of Examples and Comparative Examples wereeach visually observed for the extent of beading and evaluated inaccordance with the following evaluation criteria.

[Evaluation Criteria]

5: uniform printing was yielded without causing beading

4: occurrence of slight beading was confirmed, but it was not at allnoticeable

3: occurrence of beading was confirmed, but it does not impair the imagequality

2: occurrence of beading was clearly confirmed

1: occurrence of serious beading was confirmed

3. Evaluation of Image Density

Magenta solid image portions of Examples and Comparative Examples weremeasured for optical density, using X-RITE 932, and evaluated inaccordance with the following evaluation criteria.

[Evaluation Criteria]

A: 1.6 or greater in magenta image density

B: 1.3 or greater in magenta image density

C, 1.0 or greater in magenta image density

D: less than 1.0 in magenta image density

4. Evaluation of Glossiness

Image portions of Examples and Comparative Examples were visuallyobserved for the extent of glossiness and evaluated in accordance withthe following evaluation criteria.

[Evaluation Criteria]

A: high glossiness was confirmed

B: glossiness was confirmed

C: glossiness was slightly confirmed

D: glossiness was not confirmed

(2) Image Reliability

<Evaluation of Abrasion Resistance>

Images of black, cyan, magenta, yellow, red, green and blue in the shapeof squares each having a size of 3 cm×3 cm were formed and used forevaluation. Twenty four hours after the squares had been printed ontosheets of paper, a white cotton cloth (JISL 0803, Cotton No. 3) stuckonto a friction member with a two-sided adhesive tape (#4016, t=1.6;produced by Sumitomo 3M Limited) was rubbed back and forth five timesagainst each square using a clock meter (Model GM-1), then the densityof the coloring material attached to the cotton cloth was measured usinga spectrophotometric colorimetry densitometer (Model-938, manufacturedby X-Rite, Inc.).

[Evaluation Criteria]

A: less than 0.05 in the density of the coloring material attached tothe cotton cloth

B: 0.05 or greater, and less than 0.08 in the density of the coloringmaterial attached to the cotton cloth

C: 0.08 or greater, and less than 0.1 in the density of the coloringmaterial attached to the cotton cloth

D: 0.1 or greater in the density of the coloring material attached tothe cotton cloth

The evaluation results are shown in Table 6.

TABLE 6 Coloring Ink Abrasion material Paper strike-through BeadingDensity Glossiness resistance Example 3 Pigment Paper 1 A 4.5 (A) B B BExample 4 Pigment Paper 3 A 4.5 (A) B B A Example 5 Pigment Paper 5 A4.0 (B) B B B Example 6 Pigment Paper 6 A 4.0 (B) B B B Example 7Pigment Paper 7 A 4.5 (A) B B B Example 8 Pigment Paper 2 A 4.0 (B) B BB Example 9 Pigment Paper 2 A 4.0 (B) B B B Comparative Dye Paper 7 C1.0 (D) D C D Example 3 Note: beading ranked as 4.5 is at the levelintermediate between rank 5 and rank 4 according to the relevantevaluation criteria

1. An ink-jet recording ink comprising: water, a water-soluble organicsolvent, a pigment (P1) as a colorant (B), and at least onefluorochemical surfactant selected from compounds represented byStructural Formula (1) below,

where R₁ denotes any one of a hydrogen atom, an alkyl group and afluorine-containing group, Rf denotes a fluorine-containing group, andeach of x, y and z denotes an integer of 1 or greater.
 2. The ink-jetrecording ink according to claim 1, further comprising awater-dispersible resin (A), wherein the water-soluble organic solventis at least one selected from the group consisting of glycerin,trimethylolpropane, ethylene glycol, diethylene glycol, triethyleneglycol, propylene glycol, dipropylene glycol, tripropylene glycol,1,3-butanediol, 2,3-butanediol, 1,4-butanediol, 3-methyl-1,3-butanediol,1,5-pentanediol, 1,6-hexanediol, 2-methyl-2,4-hexanediol, 2-pyrrolidone,N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, tetramethylureaand urea.
 3. The ink-jet recording ink according to claim 2, wherein thewater-dispersible resin (A) contains at least one of an anionicself-emulsifiable ether-based polyurethane resin emulsion and anacrylic-silicone resin emulsion.
 4. An ink cartridge comprising: acontainer to house an ink-jet recording ink which comprises water, awater-soluble organic solvent, a pigment (P1) as a colorant (B), and atleast one fluorochemical surfactant selected from compounds representedby Structural Formula (1) below,

where R₁ denotes any one of a hydrogen atom, an alkyl group and afluorine-containing group, Rf denotes a fluorine-containing group, andeach of x, y and z denotes an integer of 1 or greater.
 5. An ink-jetrecording method comprising: performing recording with the use of acombination of an ink jet recording ink and a recording medium, whereinthe ink-jet recording ink comprises water, a water-soluble organicsolvent, a pigment (P1) as a colorant (B), and at least onefluorochemical surfactant selected from compounds represented byStructural Formula (1) below, wherein the recording medium is an ink-jetrecording medium for pigment ink, which includes a support containingcellulose pulp, and one or more pigment penetration preventing layers onone or both surfaces of the support, with the one or more pigmentpenetration preventing layers containing 30% by mass or more of aninorganic pigment (P2) that is different from an alumina hydrate andthat has a refractive index of 1.5 or greater, and containing 10% bymass or less of a pigment (P2) that has a refractive index of less than1.5, and wherein the amount of the ink-jet recording ink attached ontothe recording medium is 15 g/m² or less,

where R₁ denotes any one of a hydrogen atom, an alkyl group and afluorine-containing group, Rf denotes a fluorine-containing group, andeach of x, y and z denotes an integer of 1 or greater.